LA Daily News

Master Gardener: What to do about itty bitty oranges

Also, if you have an ash tree and the leaves are shriveling up and falling off, anthracnose may be your problem.

Q: My Valencia orange tree, 40-plus years old, has always put on a good crop of large fruit and last year, with all the rain, it produced extraordinarily large oranges. This year’s crop produced a good yield, but the fruit are much smaller. Do you have any idea why they are so much smaller this year?  They are still sweet and juicy.

A: If your tree still looks healthy and is producing fruit, it may just need some fertilizer. I recommend using granular fertilizer especially formulated for citrus because it contains all the micronutrients that citrus needs. As always, follow the package directions for proper dosage and frequency of application.

Most ornamental trees do not require much fertilization, especially if you mulch over their root zone with finished compost. Fruit trees, however, require a little extra help. When you harvest your fruit crop, you are removing nutrients from the tree, so those nutrients need to be replenished. Mulching with compost is still beneficial, but most fruit trees, especially citrus, need a little extra help after fruiting.

Just like what mom always told you (well, at least my mom)— when you take something, remember to put it back!

This distorted leaf from a Modesto ash tree with irregular dark brown or black indented lesions indicates that the tree has a fungal disease. (Courtesy of Paul Wessel)

Q: Laura, I have this ash tree in my backyard and for the last five days all the leaves are shriveling up and blowing off with just a slight breeze. I have enclosed two photos and I am hoping you can identify the problem. Do I need to do anything or is this just a cycle that it will go through occasionally?

A: One of your photos shows a slightly distorted leaf with irregular dark brown or black indented lesions. You also sent a photo that shows that your tree is dropping quite a few leaves (defoliation).

Anthracnose is a group of fungal diseases that produces these symptoms. Modesto ash and American sycamore are particularly susceptible.

Mild infection causes some leaves to exhibit spotting and curling, but heavy rain during a tree’s growth spurt can result in a rather severe infection that leads to significant leaf drop. In this case, after the infected leaves have fallen, a second growth flush often occurs to replace the lost foliage.

If anthracnose appears several years in a row, it can permanently damage and weaken a tree. A single year’s infection will normally not cause lasting harm.

Rake up the fallen leaves and dispose of them in the trash (do not compost). Improved air circulation is beneficial, so make sure your tree is not crowded. Have the tree professionally pruned in the winter so that the canopy can be opened, which will improve your tree’s health. Do not “top” the tree because this will lead to abnormal growth that will destroy the tree’s form and make is susceptible to wind damage.

If anthracnose infection is a yearly occurrence, anti-fungal spray may be needed. Your tree is quite large, so this may be an expensive solution. Anti-fungal treatment should be applied early in the year, just as the buds begin to open but before heavy rains.

Have gardening questions? Email

Looking for more gardening tips? Here’s how to contact the Master Gardener program in your area.

Los Angeles County; 626-586-1988;

Orange County; 949-809-9760;

Riverside County; 951-683-6491 ext. 231;

San Bernardino County; 909-387-2182;