Mostly tomatoes

Linda Workman Smith
Multi-County Master Gardener Association

Oh…my…goodness! Can you believe the rain this spring, here in our part of Oklahoma?

My two “outside” members of the Three Dog Circus/Two Acre Paradise have been muddy, up to their ears, for days!

I have tomato and pepper plants 10 to 15 inches tall, in 4-inch pots, waiting to be planted.

Thank God I got several tomato plants into ground between some of the earlier deluges.

They don’t look the best but are perking up and putting on new growth.

Several diseases love rainy weather:

According to OSU, diseases of tomato caused by bacteria, viruses and nematodes can be severe, reduce tomato yield and quality and generally are more difficult to control than those caused by fungi. Management of these diseases is most effective with the integrated use of practices such as crop rotation, resistant varieties, sanitation and disease exclusion.

Bacteria are microscopic, single-celled organisms. Bacteria multiply rapidly by simple cell division and absorb nutrients from their immediate environment. Bacterial pathogens are introduced to new sites on contaminated seed or transplants. Once established, bacteria are spread by splashing rain, water runoff, wind-driven rain or mists (aerosols), equipment, insects and people working around the plants. Bacteria persist in and around tomato plantings in weeds, volunteer plants, infested crop debris and as symptomless colonizers of plant surfaces. I will address the two that seem to affect my tomatoes most.

Early blight: As the name suggests, this disease afflicts on tomato leaves early in the growing season, and can cause trouble all season long if you don’t act quickly. This affliction first appears as little brown spots on the plant’s leaves, which then spread outwards and become a lot more noticeable. Eventually, the infected leaves will fall off the plant. It is a tough fungus that can survive in soil even over the winter. The easiest way to prevent it is to mulch your tomato plants immediately after planting, which prevents the spores in the soil from creeping up and infecting your plants. When you see tomato blight, snip off infected leaves (and remove from garden) to prevent it from spreading.

Bacterial Spot: This is a widespread disease of tomato in Oklahoma, and can be particularly severe in eastern Oklahoma, where rainfall and humidity levels promote disease development (sound familiar?). Bacterial spot reduces tomato yield and quality by defoliation and spotting of fruit. Bacterial spot is also a serious disease of pepper. The bacteria survive on diseased plant debris and on tomato seed. Leaves, stems and fruit may be infected at any growth stage when plants are wet and temperatures range from 75 F to 86 F. The bacteria enter plants through natural openings or wounds. Leaf spots are dark brown in color, appear greasy when leaves are wet and rarely exceed 1/8 inch in diameter.

It is imperative to start with clean seed and transplants. Transplants should be started from clean seed produced in an area where the disease does not occur, or from seed that is disinfested with hot water or chlorine bleach treatment. Hot-water treatment involves soaking seed at exactly 122 F for 25 minutes to 30 minutes, followed by cooling, drying and treatment with a fungicide for control of seed rot and damping off. However, germination of weak seed (more than one year old), pepper seed or excessively heated seed may be reduced by this treatment. The chlorine treatment involves soaking seed in a solution of one part household bleach and two parts water for one minute followed by rinsing, drying and treatment with a fungicide.

Crop Rotation: I cannot stress enough the importance of rotation of crop food families from year to year. If possible don’t plant members of the same food family in the same space but every 3-4 years.