Selecting proper seed and preparing the soil are a good beginning. Select healthy plants if you are planning to transplant. This keeps disease from being introduced and multiplying. Uproot diseased plants to prevent further infection.
Watering early in the day is usually the most appropriate time. Leaves then have time to dry before overnight temperatures settle in. The spread of disease can be influenced by your watering practices. If water splashes off one diseased plant onto another plant, then the disease plant may infect the healthy plant. Rainfall can produce the similar situation. Be sure to space your plants out.
Viruses are spread by other forms of contact, too. Insects may carry them from one to the next. So, keeping the insect population under control provides benefits beyond preventing them from eating your plants. But animals and gardeners can spread them, as well. Tobacco mosaic virus may be spread from the gardener’s glove and on the legs of rabbits, for example.
Weeding your garden can also lower chances of disease. Many organisms thrive on weeds and will then enjoy your vegetables. These organisms can be transported by water movement, wind, and other vehicles.
Being able to recognize the signs of various diseases, many of which are distinctive to a particular vegetable, can help control them.
When the out edges of lettuce touch the ground, lettuce mold can appear as a wet rot. The Sclerotinia mold is white and Botrytis mold is gray. The problem can be contained by removing the mold by extracting infected sections, or an entire plant.
Leafy vegetables commonly encounter spinach mosaic virus as well. In this case, leaves become mottled, and may later turn yellow. The plant appears wilted and stunted. Choosing resistant varieties can eliminate this problem altogether.
Fusarium can cause asparagus to wilt or rot. The spears look spindly and shoots may become yellow. The roots may rot and become discolored. Eliminate the infected plants by thinning the crop. Another common problem with asparagus is rust, cause by Puccinia fungus. Red spots appear on the shoots of spears. This fungus may survive through the winter. Prevent rust by avoiding excessive watering.
Other conditions that affect tomatoes are leaf spots and blight. If the summer has been cool, these will usually appear by mid-August. There are also fungi in the soil that can affect tomatoes. The roots of walnut trees can carry a harmful toxin to tomato plants. Dark concentric rings will appear on leaves with this condition. Allowing the leaves to dry before sunset will help you prevent these problems.
You will optimize your chances of a healthy, abundant crop if you can recognize and treat the signs of disease in the early stages.