by Matt Gibson
Crown rot is a nasty disease that affects many plants, mainly garden vegetables. This garden malady is caused by a fungus that sometimes develops in the soil when the location has experienced many heavy rains, flash floods, or other reasons for lots of lots of water in one location. Crown rot is very hard to notice, and once it has set in and the damage is done, there is nothing that you can do to bring the plant back from it. That means the only way to fight crown rot and win is by preventing this disease from ever damaging your garden in the first place.
How to Identify Crown Rot in Action
For the most part, crown rot goes unnoticed when it starts to affect its victim. If you look closely at an infected plant, you’ll be able to notice the signs of dry rot occurring near the crown or lower stem of the plant near the soil line. Other than this visual sign, symptoms of crown rot are often missed completely until the plant is beyond saving. Sometimes rotting will only appear on one side of the plant or on just the lateral branches before it spreads to the rest of the plant. As the rot sets in, the leaves and stems tend to become a bit discolored, turning tan or dark brown where the plant tissue has died due to the rot.
As the disease spreads, the plant will begin to wilt and die. The leaves may turn odd colors, such as yellow, purple, or red, and the growth of the plant usually becomes stunted. If crown rot has taken over at the base of a tree, dark areas develop on the bark near the crown and a dark sap runs out of the areas that are affected with the disease. This progression of the disease continues to take place even though affected plants may occasionally bloom, which sometimes leads gardeners to believe that the disease taking hold of their plants infected with crown rot isn’t serious. That’s one reason it’s so important to be familiar with the symptoms of crown rot and take action early.
What to do if You Spot Crown Rot in Your Garden
Once the first signs of crown rot catch your eye, it’s best to go ahead and take action immediately. Pull all infected plants up immediately, and discard them carefully and quickly, before the outbreak spreads and starts to affect nearby plants. Sanitize the area thoroughly, and amend the soil in the affected area so that crown rot won’t come back to haunt you in the same place twice.
To amend your soil, add lots of rich, light soil to areas with heavy or clay-like soil until the mixture seems balanced with equal parts heavy and light soil. This mixture will provide the area with ample drainage in future rains. Watch out for overly wet soil around your garden’s plants and trees. Only water each plant when necessary, and let the top inch or two of soil dry out completely before you add any water. When it’s time to water, be sure to water deeply so that the root structure of the tree or plant gets the most out of it, which will allow you to conserve water by tending your garden less often.
How to Prevent the Spread of Crown Rot
Whatever tools you use to haul away infected soil must be washed and sanitized thoroughly. You don’t want to spend all this time and energy battling crown rot just to reinfect your garden with compromised tools. Use a wheelbarrow to haul off all contaminated soil, and make sure to wash it out afterward. Even the wheels of the wheelbarrow may have been contaminated, so be thorough and attend to all parts of the wheelbarrow when you clean it. Don’t forget to also clean and sanitize any of the digging tools you used to remove infected soil, as well as the shoes you were wearing when you carried out the task.
What You Can Use to Treat Crown Rot
Fungicide can help as a preventive treatment, but it is usually ineffective once crown rothas a hold on its victim. Use two tablespoons of Captan or Aliette fungicide to every one gallon of water you’ll use, and soak the soil deeply while it is mostly dry to allow the treatment to penetrate deeply into the soil. Using plenty of fungicide will help make sure you avoid future outbreaks of crown rot in your garden.
Rotating vegetable crops every couple of seasons will help avoid crown rot as well. Especially with tomatoes—be sure to move tomato plants’ to new locations in your garden every year. Adding gravel to your soil will also help with the drainage issues that can lead to crown rot. Avoid cultivating plants in very shady areas, as lack of sun will keep the ground from drying out completely after heavy rains.
How to Move Forward After Beating Crown Rot
After you have successfully removed all the infected soil and the crown rot that invaded your garden is no longer a threat, it’s smart to take steps to avoid this fungal disease from rearing its ugly head in your garden again. Pick the ideal locations for your plants, which means choosing places that get at least six hours of direct sunlight each day. Assess the soil before planting in a new area. If it doesn’t seem like it will provide enough drainage, counter that by treating the soil with gravel, or replace the soil completely before you begin to plant for the season.
Most importantly, from now on, be careful to only water your plants when they truly need it. Do your homework on each plant’s care needs so you give each species only the amount they need and nothing more. Do not let the crowns of your plants remain submerged in water for periods of longer than four hours.
Space plants out in your garden properly. If you don’t give each specimen the room it needs to expand, the soil will become too crowded, forcing roots to fight for room to spread out so they can take in nutrients. Good airflow is the key to good drainage, so making sure your soil is properly aerated is vital to ensuring your garden doesn’t stay too wet.
Even if you’ve never had a crown rot outbreak, to prevent the possibility in the future, don’t be afraid to use a fungicide preventively to keep your soil in check. There is nothing like the hard work of carting off several wheelbarrows full of soil infected by crown rot to illustrate the importance of taking preemptive steps to keep it from attacking your garden.
Above all, don’t feel discouraged as you battle against crown rot. Even the most seasoned gardeners can tell you about plants they’ve lots in bouts with this disease. In gardening, as with most walks of life, we learn as we go—or as we grow, as the case may be.
Want to learn more about how to treat crown rot?
Gardening Know How covers Crown Rot Disease
SFGATE Homeguides covers How to Treat Crown Rot
Missouri Botanical Garden covers Crown Rot of Perennials (Southern Blight)
Plant Care Today covers Crown Rot