Should You Compost Blighted Tomato Plants?

Tomato Blight is a devastating fungus that can wipe out your entire tomato garden in less than one month. There’s little you can do about blight once it infects your plants, as organic treatments for control of blight are only effective before the fungi appear. This is the same disease responsible for the Irish potato famine in the 19th century.

In 2009, tomato blight in the form of late blight destroyed a high percentage of farm and garden tomatoes in Pennsylvania and other spots in the eastern U.S. The question for gardeners after the blight was whether to compost or destroy the infected plants.

Is it safe to compost diseased tomato plants?

Beth K Gugino, Ph.D., Assistant Professor Of Plant Pathology at Penn State University, writing in “The Vegetable And Small Fruit Gazette” says, “In theory, if done correctly, plants with late blight can be disposed of by composting. However, often this is not achieved. Proper composting involves going through both the active and curing phase of composting. The duration of the process is dependent on the inputs (original materials), composting method used and compost pile management; it can take as little as 3 months or as long as a year. The composting of diseased plant material and weeds is generally not recommended because of the potential spread of weed seeds and disease-causing pathogens when the compost is applied and incorporated back into the garden. Plant tissue can survive in the center of a warm compost pile. As long as the plant tissue is alive, the pathogen can survive.

“…Next season it will be important to destroy all volunteer tomato plants. Make sure that all late blight infected tomato plant and fruit tissue from this season is dead/destroyed. Once dead, the pathogen can no longer survive since it is an obligate pathogen (requires living plant tissue to survive overwinter) and cannot survive outside a living host. The late blight pathogen cannot survive in infested dead plant debris.

“Next year, make sure to plant healthy disease-free transplants. Examine your plants regularly for symptoms of late blight, especially if cool, wet conditions prevail like this past year. In general, good disease management focuses on creating a less favorable environment for the pathogen. The pathogen survives and spreads more effectively when leaf surfaces are wet. Avoid wet leaves by watering at the base of the plant or by using overhead irrigation during mid-morning so the leaves dry quickly. Improve air circulation by spacing plants farther apart and eliminating weeds. These practices will also help with the management of other common tomato diseases.”

So there you have it from a scientist. If you’re an expert composter and know exactly what you’re doing, feel free to compost your tomato plants. If there’s any doubt about the temperature of your compost pile, destroy the plants to be on the safe side. The last thing you want is an infection (or re-infection) of blight in your tomato garden.