Q:Β This is the first year weβve had this much of a problem with splitting, rotting and dropping oranges from our orange tree. The tree is a semi dwarf Naval Orange tree that we planted about 10 years ago. It is now well over 10 feet tall and has been producing an abundance of oranges. I generally spray it two to three times a year for the fruit flies (with blue wings) that raise Cain eating the leaves and such. Iβve only gotten to them once this year. My problem is shown in the attached pictures. Weβve lost a good two-dozen oranges in the last month to this.Β Some fall off, and I see others that I have to take off the tree.Β Have you any ideas as to what may be causing this and what I can do to stop it?
A:Β Split fruit is generally a symptom of uneven irrigation. Itβs no surprise it would happen now with the rain we have received recently. The way to mitigate the splitting problem is to provide enough irrigation during the dry parts of the year and make sure to turn down the irrigation when you receive rain. As Ben Franklin once said, βModeration in all things β including moderation.β The recommended irrigation for citrus is once every seven to 10 days during the summer to a depth of 36 inches, once every 10 to 14 days in the spring and fall, and once every 14 to 21 days in the winter. By the way, you donβt need to spray your tree for fruit flies or any other insects for that matter. Most citrus insects are minor pests and only cause cosmetic damage to the tree and donβt affect fruit production or quality.Β So unless you are selling your oranges at the grocery store you can skip the insecticide. The big exception down the road would be the citrus psyllids that spread the citrus greening disease. So far we arenβt seeing this disease here.
Peter Warren is the urban horticulture agent for the Pima County Cooperative Extension and the UA. Questions may be emailed to tucsongardensage@gmail.com
