Disposing of problem plant debris

You’ve probably read you should remove and dispose of insect pest-infected and dis­eased plant material to reduce these problems in next season’s garden. This is not as easy as it seems. Most compost piles do not heat up and maintain hot enough temperatures to kill weeds, weed seeds, disease organisms, and insect pests. In many locations burning is not allowed and it negatively impacts air quality. So, what’s a gardener to do?

Start by calling your local municipality and asking about disposal options. Many com­munities allow you to dispose of invasive plants in the gar­bage after placing them in a clear plastic bag labeled inva­sive.

Solarization is an option for managing weeds. Place small amounts of plant debris in clear plastic bags. Then place the bags in a warm sunny lo­cation before composting. For larger quantities, set the prob­lem plant debris on a sheet of plastic and securely cover it with a 2- to 6-mil clear plas­tic tarp. The plastic helps cre­ate a greenhouse effect, trap­ping heat while blocking ac­cess to water. The seeds will sprout and then seedlings and other plants are killed by the high temperatures and lack of water. It is most effective when the days are long and hot.

This may be effective if the temperatures are hot enough to kill plant insect pests and diseases. Most plant patho­gens are killed when moist soil remains at 145°F for 30 min­utes, 160°F for bacteria, and 180°F for weed seeds.

If battling jumping worms, the University of Maryland has found creating a solarization package is effective for manag­ing them in soil, compost, and mulch. Spread a sheet of clear plastic on the ground. Place a 6 to 8” layer of mulch, com­post, or soil on the plastic tarp, leaving enough excess to wrap and completely and securely cover the enclosed material. On a sunny day, the material inside can reach 150°F. Re­search varies on the number of days needed to kill the jump­ing worms. Several University sources recommend 3 or more days of at least 104°F or 105°F to kill the eggs, cocoons, and adult jumping worms.

You may want to enlist this strategy when harvesting your compost before applying it to the soil. This extra step may help reduce the risk of intro­ducing problems back into the garden.

Burying diseased material can help reduce the source of future infection of some dis­eases. Dig a hole, fill it with plant debris, mix it with soil, and then cover it with an inch or two of disease-free soil. Speed up the decompo­sition of buried material by shredding it before burying it. Avoid growing plants suscep­tible to the disease in that lo­cation the following season.

Remember to disinfect your pots, stakes, and tools that may have housed or touched diseased plants. Disease-caus­ing organisms can survive on these items, increasing disease risk in next year’s garden. Soak pots for 30 minutes in a 10% bleach solution, rinse with clear water and air dry. Store in a clean location. This is much more effective with clay and ceramic pots than plastic. Consider rotating plantings as you would in the garden and changing display areas when using plastic containers if you do not want to dispose of them.

Disinfect garden tools by dipping them in a 70% alcohol solution using rubbing alcohol or something similar for at least 30 seconds. Or you can spray your tools with a disin­fectant spray containing about 70% alcohol.

Investing time in preven­tion will result in fewer prob­lems and better results in next year’s garden.