Ongoing research

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.

Fireblight symptoms usually occur in the spring, right after a rain or even a fog drizzle. Fireblight is a disease caused by a bacterium. The bacterium, Erwinia amylovora, survives from year-to-year in the tree. It becomes active in the spring when new foliage and blossoms are developing.

Honeydew (sticky leaves) and sooty mold (black leaves) are the by-products of aphid, scale, leafhopper or whitefly activity. All the above parasites are often tended by ants which gather the honeydew and also protect the pests from their natural enemies.

Late blight is caused by a fungus, Phytophthora infestans. The spores of this fungus may have come to your yard in the fog, they may be present in your yard in the garden soil, or you may have bought them at the garden store and brought them home on the seedling tomatoes.

As the name implies, it feeds on a number of plants including fruit trees, citrus, grapes, garden vegetables, ornamentals, and weeds. Damage in the home garden is usually light and sporadic. Usually, no control measures are needed or recommended.