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There are seven genera of powdery mildews and several hundred species. The powdery mildew that attacks roses is not the same one that attacks apples, and the one on grapes is different than the one on oak trees, etc. Fortunately, the treatment for powdery mildews is all the same.
Pumpkins and other squashes are susceptible to several viruses, which are transmitted to the plants by aphids. The aphids that fly in to the planting are the ones that bring the virus from reservoir weeds, and other plants that harbor viruses in the area around your garden.
There are many species of nematodes of which a few hundred species attack plants and animals. Root knot nematode is a microscopic worm that is non-segmented, i.e., if you magnified it many times, it would look like a snake.
There are a number of scales that can become a problem on citrus. Citricola scale, brown soft scale, black scale, and California red scale are among the most common. The scales suck sap from the tree and produce honeydew.
There are many plant viruses, and often the symptom expression of a virus is a mottled light and dark green color pattern in the leaves, especially the new growth. The leaves may be deformed and reduced in size.
The most common cause of shriveled nut meats inside a normal looking shell is inadequate or inconsistent watering. If the tree suffers even one dry period during the time when the nut meats are developing and maturing, the nut meats may shrivel. The most critical period is July through October.
This pest is very active in late summer and fall. As the worm matures, it can get up to three inches long or longer and be one-half inch in diameter. A caterpillar this size can eat its way through a lot of plant tissue in one night.
These very tiny spiders are smaller than a speck of dust when full grown. They are yellow in color and look like the top half of an exclamation point, i.e., rounded at the head, tapering to a point at the tail end.
The blister mite ( Phytotus tristriatus) is microscopic in size, and you need at least a 10 x magnification to see the mites crawling among the hairs in the blister on the undersurface of the leaves. The mites are creamy white and cigar-shaped.
By Nick Sakovich Over the past few years, Australia has been producing approximately 575,000 metric tons of total citrus per year. By far, the majority of this production is oranges, with about a 60/40 percent split between valencias and navels.
