Garden Sage: Tolerate golden wasps; excess brown spots; bacterium kills caterpillars
- Updated
Answers to your gardening questions from an expert in Southern Arizona.
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I planted last November in a raised planter three of these camellias. Two of the three are dying. The leaves dried from the top down. There are still some leaves alive/pliable on the bottom of the shrub. The third camellia is doing well. They get morning sun and are shaded most of the rest of the day.
My local nursery told me to deep water them, as they donβt like our soil in Tucson. I am currently continuing to water once a week but more deeply. Is there any chance of saving them at this point?
A:Β Camellias are not ideal plants for the desert but you can grow them if you are careful. The soil here is too alkaline for these plants so they are best grown in containers or raised beds where you can keep the soil pH on the acidic side. They also need well-drained soil with a good amount of organic matter. They donβt survive in direct sun, which may partially explain the dried leaves. Even morning sun might be too much, depending on how long they are exposed. They do better in filtered shade and protected from western exposure as you are doing. The watering advice you received is correct in the amount if the soil is drying out that quickly, although watering does nothing to affect soil pH. Plants in containers and raised beds often dry out quicker than those planted in the ground so you might need to monitor the situation more closely to determine how often to water. Small containers often need water every day.
To save your remaining plant, I recommend you make sure it is not receiving too much sun, double check the soil moisture and adjust your irrigation accordingly, and amend the soil with sulphur to lower the pH as needed. Testing your soil at a reputable lab will help determine how much sulphur to add to reach the desired pH value.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: For several weeks we have had what I call βgolden waspsβ flying around our house. On occasion two or three have made it into the house. They havenβt been aggressive, just flying around. Recently, we have noticed many of them trying to build a nest in our carport. The largest we have seen before getting rid of it has been about the size of a golf ball.
These insects have a distinctive wasp body, completely yellow (more of a golden yellow) and their wings are dark colored. We are for live-and-let-live with the wildlife in our area but we donβt think we want these guys living in the carport. Any suggestions would be most welcome.
A:Β Your golden wasps are paper wasps also known as Polistes flavus. They are members of the Vespidae family of wasps and not usually aggressive unless defending their nest. Their hanging paper nests are constructed each year using bits of bark and other similar material. These insects will make nests wherever they see a good site that protects their family from the environment and has nearby food sources.
Itβs difficult to deter them without putting up screens to block their entrance so you might have to keep up the removal, at least in the early spring until they establish nests elsewhere. Because they nest on annual cycle the mated queens that overwintered nearby will typically stay with one nest until the end of the year, adding more cells to lay more eggs as their family grows. Itβs good that you are fine with them living elsewhere because they are beneficial predators of some of our pest insects.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: We had a mountain laurel tree planted in March of 2016. Thought we followed the instructions for watering before leaving for Minnesota in May. While we were gone it was watered by the drip system. On our return in October the leaves were light green so took a sample to Civano Nursery and they said it showed that there was too much salt from not being watered deep enough. They recommended watering on a slow drip for β hours once a week, which weβve been doing. The leaves are still pale green, not showing any improvement. Now weβre wondering if thereβs any way to save the tree. Do you have any advice for us?
A: Given our salty soil and the salt contained in fertilizers, it is certainly possible your tree has an excess of salt in the root zone. A soil test would confirm this diagnosis but watering it deeply might confirm as well. The watering schedule they suggest is good for newly planted trees. Since your tree has been in the ground for a year, you can back it off a bit and water deeper. Established Texas mountain laurel trees should be watered deeply every two or three weeks to a depth of 24 to 36 inches to effectively wash the salt through the root zone. Because not all drip systems are created equal, it would be good to measure the water depth with a soil probe to make sure the running time is correct. A soil probe can be as simple as a piece of rebar that you push into the ground after irrigating to see how deep the water went. Dry soil will provide more resistance than the wet stuff and thatβs how you will know when to pull out and measure the depth.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: What can we do to save the life of our beloved cactus! It started in December with some of the brown spots and now it is spreading. It has always been protected for frost with Styrofoam cups on tips and a burlap wrap. We have noticed other cacti (Mexican Fence Post) here in Saddlebrooke have the same markings. Any help would be greatly appreciated.
A:Β Brown spots on cacti may be caused by a few different things including too much sun on newly planted cacti, damage from animals, frost, hail, some pesticides, and diseases. The spots on your cacti appear to be fungal lesions that sometimes occur when we have cool, wet weather as we did this winter. The damage is usually cosmetic and wonβt cause the death of the plant but it is also irreversible so it will remain as a scar. Now that summer-like weather has begun you should see less of this disease occurring in your neighborhood.
Q: We had a mountain laurel tree planted in March of 2016. Thought we followed the instructions for watering before leaving for Minnesota in May. While we were gone it was watered by the drip system. On our return in October the leaves were light green so took a sample to Civano Nursery and they said it showed that there was too much salt from not being watered deep enough. They recommended watering on a slow drip for β hours once a week, which weβve been doing. The leaves are still pale green, not showing any improvement. Now weβre wondering if thereβs any way to save the tree. Do you have any advice for us?
A: Given our salty soil and the salt contained in fertilizers, it is certainly possible your tree has an excess of salt in the root zone. A soil test would confirm this diagnosis but watering it deeply might confirm as well. The watering schedule they suggest is good for newly planted trees. Since your tree has been in the ground for a year, you can back it off a bit and water deeper. Established Texas mountain laurel trees should be watered deeply every two or three weeks to a depth of 24 to 36 inches to effectively wash the salt through the root zone. Because not all drip systems are created equal, it would be good to measure the water depth with a soil probe to make sure the running time is correct. A soil probe can be as simple as a piece of rebar that you push into the ground after irrigating to see how deep the water went. Dry soil will provide more resistance than the wet stuff and thatβs how you will know when to pull out and measure the depth.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I wrote earlier in the week about those pesky bugs that attack our Texas mountain laurel every year, and they have already started attacking this year. I am including a photo of the critter so that you might recommend something specific to get rid of them. There are too many to hand pick and they move really fast when trying to get away.
A:Β The critter isΒ Uresiphita reversalis, aka the genista caterpillar. They typically feed on new growth at the ends of branches on Texas mountain laurel.Β I recommend a spray of Bt (Bacillus thuringiensis) where they are feeding. Bt is a naturally occurring soil bacterium that causes disease in certain insects. Bt is considered ideal for pest management because of its specificity and because of its lack of toxicity to humans or the natural enemies of many plant pests. There are different strains of Bt, each with specific toxicity to particular types of insects so be sure to choose the strain that is labeled for caterpillar pests.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I have a problem with deer entering our yard and eating the flowers in our patio container pots. I have tried a spray-on repellent, but it hasnβt worked. A fence is not possible. Any suggestions?
A:Β Fencing is the gold standard for protecting plants from deer. Otherwise, it is a bit more of a challenge. Some people use repellents with limited success because the deer either get used to the smell or the repellent wears off. If you want to try other repellents, some people hang small cloth bags with fragrant soap in them from outside branches. Others use various types of predator urine. You could also get a big dog that will bark at the deer as needed. Another tactic is to alter your landscape so the plants are difficult to access. This might be accomplished by putting the containers behind something else that blocks the deer. If there is enough other food nearby, they may see itβs too much trouble and change their route.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: We are contemplating purchasing a home in Green Valley. There is a beautiful white oak in the front yard about 15 feet away from the home. There is a root lifting the brick pavers. How or what should I do to make sure the roots arenβt going under the foundation. Also, could I dig up that root and cut it so it doesnβt do any more damage, without hurting the tree?
A:Β The Arizona white oak (Quercus arizonica) is a beautiful tree, but unfortunately someone planted it too close to the house. The mature size of that species can be as wide as 50 feet. The problem you described could get worse as the tree matures. You should probably hire a certified arborist to take a look at the tree and determine the gravity of the situation. Some companies have an air spade to temporarily blow away the surface soil to get a better sense of where the roots are and which ones are expendable, if any. Some roots are critical to the stability of the tree so you wouldnβt want to cut away one that is preventing the tree from falling over.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I use Jobe spikes to fertilize my fruit and nut trees. Last year I fertilized in mid-February and when I went to fertilize again at the end of May, I noticed the February spikes were not used up. I use drip irrigation and put the spikes near the emitters. How long do I need to wait between refertilizing with the spikes?
A:Β It depends. Fertilizers in a solid spike or granular form are going to dissolve as a result of exposure to water and warm temperatures. The manufacturer typically recommends applying them at the drip line of your trees so that rain falling off the tree or drip irrigation properly installed there will help dissolve the fertilizer. If we have a cooler spring or not much winter rain, itβs possible the spikes will last longer than advertised. Also, you probably donβt need to fertilize throughout the year. Mature trees donβt need much fertilizer and they are able to get many nutrients from the soil. A late winter application will likely suffice for the year.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I have an area about 15 feet by 12 feet that is bordered on two sides by sidewalk on the south side of my house. I have an 8-year-old thornless mesquite tree planted in this area.Β I am worried about the possibility of the roots damaging the sidewalks. Should I remove this tree? If I do, what type of tree would you recommend for that size area that would not harm the sidewalks? This area is next to my front patio and I would like to have some shade for it.
A:Β Thornless mesquite trees are a South American hybrid also known as the Chilean mesquite. The mature size of this tree is approximately 30 feet by 30 feet and that is only the above-ground size. The roots may spread twice as far, so your sidewalk is in jeopardy.
Small trees that could fit this space include kidneywood, Texas mountain laurel, Arizona rosewood, little leaf ash, and leather-leaf acacia. These may not give the shade you desire.
A few slightly larger trees that might fit are Texas ebony, palo blanco, and cascalote. I am sure there are others, so it would be good to visit our local nurseries to see what they have available.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I have three of these in my yard, plus three that came up recently in disturbed ground. What is it?
A:Β Your plants are called Senna phyllodinea, or desert Senna or silver leaf cassia. It is native to Australia and does well here. It can propagate by seed. The slender silver leaves are a good desert adaptation for reflecting the sun and reducing exposure to it. They can grow into a large shrub of 6 feet by 6 feet if allowed. The fragrant yellow flowers in February are a welcome sight for many.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: Some of my snapdragons are covered with dark spots and it seems to be spreading to neighboring plants. What can I do to stop this problem?
A:Β From examining your plant sample, the problem is a disease called snapdragon rust that is caused by the fungus Puccinia antirrhini. This is a widespread pathogen that has been around since the 1800s. Small, yellow spots on the leaves are the first indication. Unless you are paying close attention, you wonβt notice the yellow spots until they mature into chocolate-brown pustules. The spores that emerge from these pustules are spread by wind mostly but also possibly by rain and insects. The infection and incubation of these spores occurs best when temperatures are between 50 and 75 degrees, and that is what we have been experiencing in recent weeks.
Once temperatures exceed 90 degrees or so, the spores cannot survive. Infested plants can be removed and destroyed to reduce the immediate source of spores. There are also fungicides available to manage the rust if removing the plants isnβt in the plan. Look for products labeled for managing rust on landscape plants. Rust-resistant varieties of snapdragons are available. Planting them with space between to allow for air circulation is helpful, as is making sure to use drip irrigation rather than overhead sprinklers.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I live in Tucson. Alkaline soil, lots of sun, not much rain. I have found contradictory info on fertilizing Tecomas. Local websites either say βresponds well to regular fertilizer,β βfertilize with ammonium sulfateβ or βthis plant particularly hates (fertilizer).β Does anyone have a decisive answer from a reliable source?
A:Β Tecoma stans, aka yellow bells, has a reputation as a tough plant that needs little help once established, except for occasional pruning and pest management. Although I couldnβt find any research detailing its exact needs, all plants need water and nutrients.
If you want to have your soil tested by a laboratory, many of them will make fertilizer recommendations based on the results and which plants you are planning to grow. If you would rather experiment without a soil test, I recommend a slow release tree and shrub fertilizer in the spring and also recommend regularly scheduled drip irrigation every two or three weeks unless it is raining.
You can use composted manure or another organic material that has been composted as a slow-release fertilizer. In the end, your plants will help you figure out their needs by how well they appear and grow. For example, plants that begin to have yellow leaves with green veins are often showing a sign of nutrient deficiency. Taking a look at your landscape plants once a week or so to see if problems are occurring is one of the cornerstones of integrated pest management and a great way to catch problems before they get out of hand.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I have had two mountain laurel bushes for 15 yearsΒ . Suddenly last fall, one droppedΒ Β its leaves. The stems were green andΒ it is starting to bloom and add some new leaves. The other bush had some white places, not sure if there was an aphid attack, I did not notice a lot of this white on the bad plant.
A:Β Texas mountain laurel (Calia secundiflora) are fairly tough plants and have only a few minor insect problems that may cause limited defoliation or distortion from feeding.
Losing all the leaves as you describe is likely some sort of environmental stress. Consider what irrigation your plants receive since that is a limiting factor for most plants. Dropping leaves and blossoms is a normal reaction to lack of water. Leaves are where water vapor leaves a plant so to reduce the amount of water escaping; the plant may drop its leaves.Β Itβs good to see the leaves are growing back.Β Itβs possible the plant will grow much better with all the rain weβve had along with continued irrigation through the warmer months.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I have been collecting compost material in my kitchen then burying it directly in my garden for several years. I didnβt plant a garden this year but still bury fruits and vegetables.Β Β This year I discovered what I think are grubs. How can I get rid of them?
A:Β The grubs are in your soil because you made it so nice for them. These beetles do best in soil rich in organic matter because they feed on it and so the adult beetles will lay eggs where they find good soil or directly into compost piles. You can get rid of themΒ Β if your garden is small and you donβt mind sifting through the dirt.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I had some lower branches trimmed from my ponderosa pine in December. How long will it take for the sap to quit flowing?
A:Β Sap flowing from a tree wound is part of its defense systemΒ . The sap flow will continue until the vessels clog and the tree seals the wound. There is no need for anything to be applied. Applying something to the wound is not good for the tree.Β It used to be a common practice to paint pruning wounds but it turns out trees do a better job of sealing their own wounds and the paint sometimes hinders that process.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I have researched and talked to many people about how to kill Bermuda grass most effectively while being as environmentally friendly as you can be. I have heard of several different methods, including covering the whole area in plastic as well as using Roundup as possible methods. I would like your opinion on the best method to use to kill Bermuda grass. My understanding is the only chemical way to do it would be with Roundup, but my wife is very against that idea. I have read the research on the biochemical makeup of Roundup and I am not sure if it is truly toxic if you only use that one to two times.
A:Β Roundup or any other product containing the active ingredient glyphosate is the most effective and least labor-intensive way to manage/kill Bermuda grass and many other weeds. It does require repeat applications and the grass needs to be green when you spray to be most effective. Other methods include scraping off the top layer of grass and covering it with landscape fabric, clear plastic, or cardboard, and digging the grass up with a shovel. You can certainly kill much of the grass through solarization, starvation, or digging it up. The problem, as you may know, is the roots, or parts of them, are still alive in the soil in many cases with all of these methods. They will eventually find a way around or through the covers so it may be more labor intensive to manage it. Bermuda grass spreads by underground stems (rhizomes) and aboveground runners (stolons), not to mention seed. A systemic herbicide can get to the root of the problem with less effort. No matter which method you choose, if you live in an area with unmanaged Bermuda grass nearby, it will eventually return so you need to remain vigilant in your management. Regarding the toxicity, according to the Monsanto label, glyphosate is a moderate irritant if eyes and skin are exposed but is practically nontoxic otherwise unless you are an aquatic organism. As always, it is best to follow the instructions on the label of any pesticide to avoid harming any non-target organisms.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I read your article about Bermuda grass and have a question concerning the condo development where we live. The complex includes a large area of grass and mesquite trees. The HOA overseeds in the winter. This makes for a beautiful green area and also greatly cuts down on blowing dust. The landscaping company has advised the HOA to not overseed every three years to help the Bermuda grass. Does this make sense to you? I see many places (e.g. golf courses) that overseed every year and the Bermuda grass appears to come in just fine.
A:Β Yes, it makes sense. Continuous overseeding can cause stress to Bermuda grass if proper care is not taken for proper overseeding timing/preparation and proper spring transition back to healthy Bermuda grass conditions. Rye grass is a common cool season grass used to overseed Bermuda grass in the fall. Extended rye grass seasons on the front end from early overseeding and well beyond spring transition into summer will weaken the root system and reproductive capabilities of Bermuda grass. If these unhealthy practices are repeated annually, exhausted and stressed Bermuda grass diminishes over time and requires renovation. Thus, skipping overseeding every few years can provide the Bermuda grass a nice long growing season from March to November to rebuild roots. If the stress is minimized by best management practices and a good 100 days of optimal growing conditions are provided each year, Bermuda grass can be overseeded regularly. The minimum 100 days should be in the June through September timeframe. For more details on the timing and preparation, there is a nice publication available online by the University of Arizona turf grass specialists, David Kopec and Kai Umeda.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: How do I keep cockroaches from invading my house from outside?
A:Β There are many species of cockroaches and only a few of them like to live with humans. For some species, entering your home is an accident and they can be dispatched with a broom. They are nocturnal and attracted to lights, water, food, and shelter. To protect your home, make sure itβs difficult for them to get inside by sealing any holes in the foundation, making sure door sweeps are in good condition, or traps can be used.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
- Updated
Q: I have a clean yard, in which I have a few plants and trees, and had a large Mexican primrose that came up by itself. Last week gophers, plural, got the primrose and it disappeared. How did they find it? The ground for more than 40 feet around the primrose is bare and had no gopher mounds of dirt. Nothing, yet the tunnel surfaced an inch from the plant and they proceeded to eat it. I set a trap and killed one gopher overnight, but the next day there was an additional mound and the plant had disappeared. Do they come above ground to scout around at night? Iβm mystified.
A:Β Gophers are nocturnal so it makes sense that you could catch them overnight and lose plants to them at the same time. Their crescent-shaped mounds, tunnels, and plant damage are certainly signs they are present. Many animals find plants by smell and they may have been scouting above ground at night before building that part of the tunnel. While they feed on the roots primarily, they will also take whole plants underground. Continue trapping and try to exclude them from desired plants with hardware cloth buried beneath the beds.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I planted last November in a raised planter three of these camellias. Two of the three are dying. The leaves dried from the top down. There are still some leaves alive/pliable on the bottom of the shrub. The third camellia is doing well. They get morning sun and are shaded most of the rest of the day.
My local nursery told me to deep water them, as they donβt like our soil in Tucson. I am currently continuing to water once a week but more deeply. Is there any chance of saving them at this point?
A:Β Camellias are not ideal plants for the desert but you can grow them if you are careful. The soil here is too alkaline for these plants so they are best grown in containers or raised beds where you can keep the soil pH on the acidic side. They also need well-drained soil with a good amount of organic matter. They donβt survive in direct sun, which may partially explain the dried leaves. Even morning sun might be too much, depending on how long they are exposed. They do better in filtered shade and protected from western exposure as you are doing. The watering advice you received is correct in the amount if the soil is drying out that quickly, although watering does nothing to affect soil pH. Plants in containers and raised beds often dry out quicker than those planted in the ground so you might need to monitor the situation more closely to determine how often to water. Small containers often need water every day.
To save your remaining plant, I recommend you make sure it is not receiving too much sun, double check the soil moisture and adjust your irrigation accordingly, and amend the soil with sulphur to lower the pH as needed. Testing your soil at a reputable lab will help determine how much sulphur to add to reach the desired pH value.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: For several weeks we have had what I call βgolden waspsβ flying around our house. On occasion two or three have made it into the house. They havenβt been aggressive, just flying around. Recently, we have noticed many of them trying to build a nest in our carport. The largest we have seen before getting rid of it has been about the size of a golf ball.
These insects have a distinctive wasp body, completely yellow (more of a golden yellow) and their wings are dark colored. We are for live-and-let-live with the wildlife in our area but we donβt think we want these guys living in the carport. Any suggestions would be most welcome.
A:Β Your golden wasps are paper wasps also known as Polistes flavus. They are members of the Vespidae family of wasps and not usually aggressive unless defending their nest. Their hanging paper nests are constructed each year using bits of bark and other similar material. These insects will make nests wherever they see a good site that protects their family from the environment and has nearby food sources.
Itβs difficult to deter them without putting up screens to block their entrance so you might have to keep up the removal, at least in the early spring until they establish nests elsewhere. Because they nest on annual cycle the mated queens that overwintered nearby will typically stay with one nest until the end of the year, adding more cells to lay more eggs as their family grows. Itβs good that you are fine with them living elsewhere because they are beneficial predators of some of our pest insects.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: We had a mountain laurel tree planted in March of 2016. Thought we followed the instructions for watering before leaving for Minnesota in May. While we were gone it was watered by the drip system. On our return in October the leaves were light green so took a sample to Civano Nursery and they said it showed that there was too much salt from not being watered deep enough. They recommended watering on a slow drip for β hours once a week, which weβve been doing. The leaves are still pale green, not showing any improvement. Now weβre wondering if thereβs any way to save the tree. Do you have any advice for us?
A: Given our salty soil and the salt contained in fertilizers, it is certainly possible your tree has an excess of salt in the root zone. A soil test would confirm this diagnosis but watering it deeply might confirm as well. The watering schedule they suggest is good for newly planted trees. Since your tree has been in the ground for a year, you can back it off a bit and water deeper. Established Texas mountain laurel trees should be watered deeply every two or three weeks to a depth of 24 to 36 inches to effectively wash the salt through the root zone. Because not all drip systems are created equal, it would be good to measure the water depth with a soil probe to make sure the running time is correct. A soil probe can be as simple as a piece of rebar that you push into the ground after irrigating to see how deep the water went. Dry soil will provide more resistance than the wet stuff and thatβs how you will know when to pull out and measure the depth.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: What can we do to save the life of our beloved cactus! It started in December with some of the brown spots and now it is spreading. It has always been protected for frost with Styrofoam cups on tips and a burlap wrap. We have noticed other cacti (Mexican Fence Post) here in Saddlebrooke have the same markings. Any help would be greatly appreciated.
A:Β Brown spots on cacti may be caused by a few different things including too much sun on newly planted cacti, damage from animals, frost, hail, some pesticides, and diseases. The spots on your cacti appear to be fungal lesions that sometimes occur when we have cool, wet weather as we did this winter. The damage is usually cosmetic and wonβt cause the death of the plant but it is also irreversible so it will remain as a scar. Now that summer-like weather has begun you should see less of this disease occurring in your neighborhood.
Q: We had a mountain laurel tree planted in March of 2016. Thought we followed the instructions for watering before leaving for Minnesota in May. While we were gone it was watered by the drip system. On our return in October the leaves were light green so took a sample to Civano Nursery and they said it showed that there was too much salt from not being watered deep enough. They recommended watering on a slow drip for β hours once a week, which weβve been doing. The leaves are still pale green, not showing any improvement. Now weβre wondering if thereβs any way to save the tree. Do you have any advice for us?
A: Given our salty soil and the salt contained in fertilizers, it is certainly possible your tree has an excess of salt in the root zone. A soil test would confirm this diagnosis but watering it deeply might confirm as well. The watering schedule they suggest is good for newly planted trees. Since your tree has been in the ground for a year, you can back it off a bit and water deeper. Established Texas mountain laurel trees should be watered deeply every two or three weeks to a depth of 24 to 36 inches to effectively wash the salt through the root zone. Because not all drip systems are created equal, it would be good to measure the water depth with a soil probe to make sure the running time is correct. A soil probe can be as simple as a piece of rebar that you push into the ground after irrigating to see how deep the water went. Dry soil will provide more resistance than the wet stuff and thatβs how you will know when to pull out and measure the depth.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I wrote earlier in the week about those pesky bugs that attack our Texas mountain laurel every year, and they have already started attacking this year. I am including a photo of the critter so that you might recommend something specific to get rid of them. There are too many to hand pick and they move really fast when trying to get away.
A:Β The critter isΒ Uresiphita reversalis, aka the genista caterpillar. They typically feed on new growth at the ends of branches on Texas mountain laurel.Β I recommend a spray of Bt (Bacillus thuringiensis) where they are feeding. Bt is a naturally occurring soil bacterium that causes disease in certain insects. Bt is considered ideal for pest management because of its specificity and because of its lack of toxicity to humans or the natural enemies of many plant pests. There are different strains of Bt, each with specific toxicity to particular types of insects so be sure to choose the strain that is labeled for caterpillar pests.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- Peter L. Warren Special to the Arizona Daily Star
Q: I have a problem with deer entering our yard and eating the flowers in our patio container pots. I have tried a spray-on repellent, but it hasnβt worked. A fence is not possible. Any suggestions?
A:Β Fencing is the gold standard for protecting plants from deer. Otherwise, it is a bit more of a challenge. Some people use repellents with limited success because the deer either get used to the smell or the repellent wears off. If you want to try other repellents, some people hang small cloth bags with fragrant soap in them from outside branches. Others use various types of predator urine. You could also get a big dog that will bark at the deer as needed. Another tactic is to alter your landscape so the plants are difficult to access. This might be accomplished by putting the containers behind something else that blocks the deer. If there is enough other food nearby, they may see itβs too much trouble and change their route.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- Peter L. Warren Special to the Arizona Daily Star
Q: We are contemplating purchasing a home in Green Valley. There is a beautiful white oak in the front yard about 15 feet away from the home. There is a root lifting the brick pavers. How or what should I do to make sure the roots arenβt going under the foundation. Also, could I dig up that root and cut it so it doesnβt do any more damage, without hurting the tree?
A:Β The Arizona white oak (Quercus arizonica) is a beautiful tree, but unfortunately someone planted it too close to the house. The mature size of that species can be as wide as 50 feet. The problem you described could get worse as the tree matures. You should probably hire a certified arborist to take a look at the tree and determine the gravity of the situation. Some companies have an air spade to temporarily blow away the surface soil to get a better sense of where the roots are and which ones are expendable, if any. Some roots are critical to the stability of the tree so you wouldnβt want to cut away one that is preventing the tree from falling over.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- Peter L. Warren Special to the Arizona Daily Star
Q: I use Jobe spikes to fertilize my fruit and nut trees. Last year I fertilized in mid-February and when I went to fertilize again at the end of May, I noticed the February spikes were not used up. I use drip irrigation and put the spikes near the emitters. How long do I need to wait between refertilizing with the spikes?
A:Β It depends. Fertilizers in a solid spike or granular form are going to dissolve as a result of exposure to water and warm temperatures. The manufacturer typically recommends applying them at the drip line of your trees so that rain falling off the tree or drip irrigation properly installed there will help dissolve the fertilizer. If we have a cooler spring or not much winter rain, itβs possible the spikes will last longer than advertised. Also, you probably donβt need to fertilize throughout the year. Mature trees donβt need much fertilizer and they are able to get many nutrients from the soil. A late winter application will likely suffice for the year.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I have an area about 15 feet by 12 feet that is bordered on two sides by sidewalk on the south side of my house. I have an 8-year-old thornless mesquite tree planted in this area.Β I am worried about the possibility of the roots damaging the sidewalks. Should I remove this tree? If I do, what type of tree would you recommend for that size area that would not harm the sidewalks? This area is next to my front patio and I would like to have some shade for it.
A:Β Thornless mesquite trees are a South American hybrid also known as the Chilean mesquite. The mature size of this tree is approximately 30 feet by 30 feet and that is only the above-ground size. The roots may spread twice as far, so your sidewalk is in jeopardy.
Small trees that could fit this space include kidneywood, Texas mountain laurel, Arizona rosewood, little leaf ash, and leather-leaf acacia. These may not give the shade you desire.
A few slightly larger trees that might fit are Texas ebony, palo blanco, and cascalote. I am sure there are others, so it would be good to visit our local nurseries to see what they have available.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I have three of these in my yard, plus three that came up recently in disturbed ground. What is it?
A:Β Your plants are called Senna phyllodinea, or desert Senna or silver leaf cassia. It is native to Australia and does well here. It can propagate by seed. The slender silver leaves are a good desert adaptation for reflecting the sun and reducing exposure to it. They can grow into a large shrub of 6 feet by 6 feet if allowed. The fragrant yellow flowers in February are a welcome sight for many.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: Some of my snapdragons are covered with dark spots and it seems to be spreading to neighboring plants. What can I do to stop this problem?
A:Β From examining your plant sample, the problem is a disease called snapdragon rust that is caused by the fungus Puccinia antirrhini. This is a widespread pathogen that has been around since the 1800s. Small, yellow spots on the leaves are the first indication. Unless you are paying close attention, you wonβt notice the yellow spots until they mature into chocolate-brown pustules. The spores that emerge from these pustules are spread by wind mostly but also possibly by rain and insects. The infection and incubation of these spores occurs best when temperatures are between 50 and 75 degrees, and that is what we have been experiencing in recent weeks.
Once temperatures exceed 90 degrees or so, the spores cannot survive. Infested plants can be removed and destroyed to reduce the immediate source of spores. There are also fungicides available to manage the rust if removing the plants isnβt in the plan. Look for products labeled for managing rust on landscape plants. Rust-resistant varieties of snapdragons are available. Planting them with space between to allow for air circulation is helpful, as is making sure to use drip irrigation rather than overhead sprinklers.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I live in Tucson. Alkaline soil, lots of sun, not much rain. I have found contradictory info on fertilizing Tecomas. Local websites either say βresponds well to regular fertilizer,β βfertilize with ammonium sulfateβ or βthis plant particularly hates (fertilizer).β Does anyone have a decisive answer from a reliable source?
A:Β Tecoma stans, aka yellow bells, has a reputation as a tough plant that needs little help once established, except for occasional pruning and pest management. Although I couldnβt find any research detailing its exact needs, all plants need water and nutrients.
If you want to have your soil tested by a laboratory, many of them will make fertilizer recommendations based on the results and which plants you are planning to grow. If you would rather experiment without a soil test, I recommend a slow release tree and shrub fertilizer in the spring and also recommend regularly scheduled drip irrigation every two or three weeks unless it is raining.
You can use composted manure or another organic material that has been composted as a slow-release fertilizer. In the end, your plants will help you figure out their needs by how well they appear and grow. For example, plants that begin to have yellow leaves with green veins are often showing a sign of nutrient deficiency. Taking a look at your landscape plants once a week or so to see if problems are occurring is one of the cornerstones of integrated pest management and a great way to catch problems before they get out of hand.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I have had two mountain laurel bushes for 15 yearsΒ . Suddenly last fall, one droppedΒ Β its leaves. The stems were green andΒ it is starting to bloom and add some new leaves. The other bush had some white places, not sure if there was an aphid attack, I did not notice a lot of this white on the bad plant.
A:Β Texas mountain laurel (Calia secundiflora) are fairly tough plants and have only a few minor insect problems that may cause limited defoliation or distortion from feeding.
Losing all the leaves as you describe is likely some sort of environmental stress. Consider what irrigation your plants receive since that is a limiting factor for most plants. Dropping leaves and blossoms is a normal reaction to lack of water. Leaves are where water vapor leaves a plant so to reduce the amount of water escaping; the plant may drop its leaves.Β Itβs good to see the leaves are growing back.Β Itβs possible the plant will grow much better with all the rain weβve had along with continued irrigation through the warmer months.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I have been collecting compost material in my kitchen then burying it directly in my garden for several years. I didnβt plant a garden this year but still bury fruits and vegetables.Β Β This year I discovered what I think are grubs. How can I get rid of them?
A:Β The grubs are in your soil because you made it so nice for them. These beetles do best in soil rich in organic matter because they feed on it and so the adult beetles will lay eggs where they find good soil or directly into compost piles. You can get rid of themΒ Β if your garden is small and you donβt mind sifting through the dirt.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I had some lower branches trimmed from my ponderosa pine in December. How long will it take for the sap to quit flowing?
A:Β Sap flowing from a tree wound is part of its defense systemΒ . The sap flow will continue until the vessels clog and the tree seals the wound. There is no need for anything to be applied. Applying something to the wound is not good for the tree.Β It used to be a common practice to paint pruning wounds but it turns out trees do a better job of sealing their own wounds and the paint sometimes hinders that process.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I have researched and talked to many people about how to kill Bermuda grass most effectively while being as environmentally friendly as you can be. I have heard of several different methods, including covering the whole area in plastic as well as using Roundup as possible methods. I would like your opinion on the best method to use to kill Bermuda grass. My understanding is the only chemical way to do it would be with Roundup, but my wife is very against that idea. I have read the research on the biochemical makeup of Roundup and I am not sure if it is truly toxic if you only use that one to two times.
A:Β Roundup or any other product containing the active ingredient glyphosate is the most effective and least labor-intensive way to manage/kill Bermuda grass and many other weeds. It does require repeat applications and the grass needs to be green when you spray to be most effective. Other methods include scraping off the top layer of grass and covering it with landscape fabric, clear plastic, or cardboard, and digging the grass up with a shovel. You can certainly kill much of the grass through solarization, starvation, or digging it up. The problem, as you may know, is the roots, or parts of them, are still alive in the soil in many cases with all of these methods. They will eventually find a way around or through the covers so it may be more labor intensive to manage it. Bermuda grass spreads by underground stems (rhizomes) and aboveground runners (stolons), not to mention seed. A systemic herbicide can get to the root of the problem with less effort. No matter which method you choose, if you live in an area with unmanaged Bermuda grass nearby, it will eventually return so you need to remain vigilant in your management. Regarding the toxicity, according to the Monsanto label, glyphosate is a moderate irritant if eyes and skin are exposed but is practically nontoxic otherwise unless you are an aquatic organism. As always, it is best to follow the instructions on the label of any pesticide to avoid harming any non-target organisms.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I read your article about Bermuda grass and have a question concerning the condo development where we live. The complex includes a large area of grass and mesquite trees. The HOA overseeds in the winter. This makes for a beautiful green area and also greatly cuts down on blowing dust. The landscaping company has advised the HOA to not overseed every three years to help the Bermuda grass. Does this make sense to you? I see many places (e.g. golf courses) that overseed every year and the Bermuda grass appears to come in just fine.
A:Β Yes, it makes sense. Continuous overseeding can cause stress to Bermuda grass if proper care is not taken for proper overseeding timing/preparation and proper spring transition back to healthy Bermuda grass conditions. Rye grass is a common cool season grass used to overseed Bermuda grass in the fall. Extended rye grass seasons on the front end from early overseeding and well beyond spring transition into summer will weaken the root system and reproductive capabilities of Bermuda grass. If these unhealthy practices are repeated annually, exhausted and stressed Bermuda grass diminishes over time and requires renovation. Thus, skipping overseeding every few years can provide the Bermuda grass a nice long growing season from March to November to rebuild roots. If the stress is minimized by best management practices and a good 100 days of optimal growing conditions are provided each year, Bermuda grass can be overseeded regularly. The minimum 100 days should be in the June through September timeframe. For more details on the timing and preparation, there is a nice publication available online by the University of Arizona turf grass specialists, David Kopec and Kai Umeda.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: How do I keep cockroaches from invading my house from outside?
A:Β There are many species of cockroaches and only a few of them like to live with humans. For some species, entering your home is an accident and they can be dispatched with a broom. They are nocturnal and attracted to lights, water, food, and shelter. To protect your home, make sure itβs difficult for them to get inside by sealing any holes in the foundation, making sure door sweeps are in good condition, or traps can be used.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
- By Peter L. Warren Special to the Arizona Daily Star
Q: I have a clean yard, in which I have a few plants and trees, and had a large Mexican primrose that came up by itself. Last week gophers, plural, got the primrose and it disappeared. How did they find it? The ground for more than 40 feet around the primrose is bare and had no gopher mounds of dirt. Nothing, yet the tunnel surfaced an inch from the plant and they proceeded to eat it. I set a trap and killed one gopher overnight, but the next day there was an additional mound and the plant had disappeared. Do they come above ground to scout around at night? Iβm mystified.
A:Β Gophers are nocturnal so it makes sense that you could catch them overnight and lose plants to them at the same time. Their crescent-shaped mounds, tunnels, and plant damage are certainly signs they are present. Many animals find plants by smell and they may have been scouting above ground at night before building that part of the tunnel. While they feed on the roots primarily, they will also take whole plants underground. Continue trapping and try to exclude them from desired plants with hardware cloth buried beneath the beds.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed toΒ tucsongardensage@gmail.com
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