Ongoing research

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Aphids on Citrus Black Fly Botrytis Brown Rot Cabbage Looper California Red Scale Codling Moth Fig Rust Fireblight Honeydew and Sooty Mold Late Blight on Tomatoes Omnivorous Leafroller Orange Worms Peach Leaf Curl Powdery Mildew Pumpkin Viruses Root Know Nematode Scale on Citrus Squash Virus Tomato...

There are several species of aphids that will infest citrus on the Central Coast. The cotton/melon aphid, Aphis gossypii feed on the underside of young leaves, causing curling and distortion. To control infestations of aphids, spray the infested foliage (no need to spray the whole tree).

Black flies, Buffalo gnats or Turkey gnats are true flies not a bee, wasp or ant. They are very small one to five millimeters long and usually black to gray in color. Black flies tend to bite where clothing fits tightly against the body.

With the late and often heavy spring rains, Botrytis gray mold has been an unusually severe problem. Rose flowers have in many instances been severely blighted. Jasmine, geranium plus other garden flowers and vegetables have also been affected.

Brown rot of apricots and other stone fruits (plums, peaches, prunes, cherries, and nectarines) can be a serious problem for Central Coast gardeners. Brown rot is caused by a fungus which can attack all parts of the tree. Buds, twigs, and fruit are the primary infection sites, however.

The cabbage looper may be more familiar to you under the name inch worm. The adult cabbage looper is a dull brownish-gray moth.

California Red Scale is a very important pest on California citrus. Lemon is most susceptible, followed by grapefruit, Valencia orange, navel orange, and Mandarin orange. Grapes, holly, olives, roses, eucalyptus, mulberry, and walnuts can also be attacked.

The first phase of codling moth control I recommend is to thin the apple crop. Apples produce fruit in clusters. When the small apples are from dime to quarter size, thin the fruit to one per cluster. If the crop is very light, leave two apples per cluster.

Fig rust is a fungus-caused disease, and the literature I have indicates that fig rust is rare in California. Control of rust on figs is going to be difficult. Very few good fungicides are registered for use on figs. In fact, my references list only two.