A website from UGA Cooperative Extension

If you’ve ever noticed your plants turning yellow, it’s possible you might be overwatering. Overwatering plants is a major cause of root damage and rot here in Georgia, only made worse by the constant humidity which prevents the plants from drying out. This article is adapted from the original (Randy Drinkard, 2004) but still provides some relevant information for why we should pay attention to how much we water our plants.

Despite recent droughts, one of the most commonly diagnosed diseases in GA is caused by excess soil water. The problem with root rot is that the symptoms are often confusing. People see plants that are wilted and yellowing, with stunted growth, and they naturally think the problem is lack of water – so they water more! Unfortunately, the causes of root rot (Pythium and rhizoctonia) are both very aggressive pathogens that thrive in wet soil.

Good Drainage– Understanding your soil’s drainage is key to better plant management. Most of our soil contains a lot of clay, which retains moisture and doesn’t drain well. Test your yard before planting by digging a 1 foot hole, filling it with water, allowing it to drain, and then filling it with water again. If it doesn’t drain fully within 24 hours, thenyou need to add topsoil, organic matter or some other amendment. Also, bring your soil to the Extension office to have a soil testdone to determine what type and amounts of fertilizer are needed to boostplant growth. It’s much easier to improve the characteristics of the soil beforeplanting than to treat diseases that might set in later.

Avoid Overwatering– One good watering each week is enough for most plants. Do, however, avoid light watering that gets the top layer of the soil wet but doesn’t penetrate the 3 to 4 inches plants really need. Often people overwater simply out of habit or because the top layer of soil is dry. It’s important to check the soil from time to time to see how well it is draining and whether plants are getting enough or too much moisture. To do this, dig about 6 inches down to see how much moisture the soil contains. Don’t dig into the root systems of plants, but rather dig around them. But make sure you get down below the root zone – about 6 inches, in most cases. If it’s dry and powdery that far down, it needs to be watered. Well-watered soil will stick together when it’s pressed into a ball.

Plant Healthy Plants– Another key to preventing root rot is to carefully check new plants before introducing them to the garden. Contaminated soil is another way that pathogens or diseases can be introduced. Take one or two plants out of a flat of bedding plants and take a close look at the roots. Roots should be white or silvery. If they’re brownish, soft or sparse, then the plant is probably infected with a root rot-causing pathogen. Don’t introduce sick plants to the growing site.

If root rot is diagnosed, fungicides are on the market that, if wisely chosen, can reduce or alleviate the problem. However, the best thing to do is to correct the real problem: overly wet soil.

The Daily Tribune News/Digging For Answers – 6/27/04