Crown Rot Identification And Tips For Crown Rot Treatment

Crown Rot Identification And Tips For Crown Rot Treatment

By: Nikki Tilley, Author of The Bulb-o-licious Garden

Crown rot commonly affects many types of plants in the garden, including vegetables. However, it can also be a problem with trees and shrubs as well and is oftentimes detrimental to the plants. So what exactly is this and how do you stop crown rot before it is too late?

What is Crown Rot Disease?

Crown rot is a disease caused by a soil-borne fungus which can survive in the soil indefinitely. This fungal disease is often favored by wet conditions and heavy soils. While symptoms may vary from plant to plant, there is often little you can do once the disease occurs.

Signs of Crown Rot Disease

While the crown or lower stem of plants affected by this disease may exhibit dry rotting at or near the soil line, most other symptoms often go unnoticed—until it’s too late. Rotting may appear on one side or only on lateral branches at first and eventually spreads to the rest of the plant. Infected areas may be discolored, usually tan or dark colored, which is indicative of dead tissue.

As crown rot progresses, the plant will begin to wilt and quickly die, with younger plants being more susceptible to death. Foliage may yellow or even turn a red to purplish color as well. In some cases, plant growth may become stunted, yet the plants may still continue to put out blooms, albeit few. Tree may develop dark areas on the bark around the crown with dark sap oozing from the edges of the diseased area.

How Do You Stop Crown Rot?

Crown rot treatment is difficult, especially if it’s not caught early enough, which is often the case. Usually, there’s little you can do to save plants, so prevention is important.

Once the first signs of crown rot are noticed, it’s best to simply pull the infected plants and discard them promptly. You’ll also need to sanitize the area and surrounding soil to keep the disease from spreading to nearby plants. Amending heavy, clay soil will help with any drainage issues that normally encourage this disease.

Avoiding overly wet soil around plants and trees is important. Water plants only when necessary, allowing at least the top inch or so of soil to dry out between watering intervals. When you do irrigate, water deeply, which will allow plant roots to benefit the most while allowing you to water less often.

Rotating vegetable crops, like tomatoes, every couple of seasons can help too.

Trees will usually not survive either, depending on how bad they’re affected. However, you can try cutting away the affected bark and removing the soil from base of the tree down to the main roots to allow the crown to dry out.

The use of fungicide can help prevent the disease but is usually ineffective once it’s completely taken hold. Captan or Aliette are most often used. Drench the soil (2 tbsp. to 1 gal. of water) while somewhat dry to allow the fungicide to penetrate well. Repeat this twice at 30-day intervals.

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While the name Phytophthora might not mean much to you, these organisms are a menace to agriculture and forests alike.

The name is derived from Greek and tells you what you need to know about them: plant destroyers.

Once thought to be fungi, these water molds are now considered a separate type of organism. However, they are as aggressive and destructive as any fungus.

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More than 100 species of Phytophthora cause a complex of diseases on hundreds of kinds of plants. Several different species can infect temperate fruit trees such apple and crabapple, pear, peach, apricot, plum, and cherry and also tropical fruit trees such as oranges, limes, and lemons.

Difficult to diagnose, these organisms can kill the fine roots (root rot), damage the roots right below the soil surface (crown rot), and rot the tree above the union (collar rot).

Read on to learn how to distinguish Phytophthora infections from other fruit tree pathogens and steps you can take to prevent these debilitating diseases.

Brian Hudelson, UW-Madison Plant Pathology and Laura Jull, UW-Madison Horticulture
Revised: 8/13/2012
Item number: XHT1070

What is root/crown rot?
Root/crown rot is a general term that describes any disease of woody ornamentals where the pathogen (causal organism) attacks and leads to the deterioration of a plant’s root system and/or lower trunk or branches near the soil line. Root rots can be chronic diseases or, more commonly, are acute and can lead to the death of the plant.

How do you know if your tree or shrub has a root or crown rot?
Gardeners often become aware of a root/crown rot when they see above ground symptoms of the diseases. Affected plants are often slow-growing or stunted and may show signs of wilting. Often the canopy of an affected tree or shrub is thin, with foliage that is yellow or red, suggesting a nutrient deficiency. Careful examination of the roots/crowns of these plants reveals tissue that is soft and brown.

Where does root/crown rot come from?
Several soil-borne fungi can cause root/crown rots, including (most frequently) Phytophthora spp., Pythium spp., Rhizoctonia solani, and Fusarium spp. These fungi have wide host ranges, and prefer wet soil conditions. Some root rot fungi such as Pythium and Phytophtora produce spores that can survive for long periods in soil.

How do I save a plant with root/crown rot?
REDUCE SOIL MOISTURE! Provide enough water to fulfill a plant’s growth needs and prevent drought stress, but DO NOT over-water. Remove excess mulch (greater than four inches) that can lead to overly wet soils. Chemical fungicides (PCNB, mefenoxam, metalaxyl, etridiazole, thiophanate-methyl and propiconazole) and biological control agents (Gliocladium, Streptomyces, and Trichoderma) are labeled for root/crown rot control. However, DO NOT use these products unless you know exactly which root/crown rot pathogen is affecting your tree or shrub. Contact your county Extension agent for details on obtaining an accurate root/crown rot diagnosis and for advice on which, if any, fungicides you should consider using.

How do I avoid problems with root/crown rots?
Buy plants from a reputable source and make sure they are root/crown rot-free prior to purchase. Establish healthy plants in a well-drained site, and when planting, place the root collar just at the soil surface. Moderate soil moisture. Add organic material (e.g., leaf litter or compost) to heavy soils to increase soil drainage and DO NOT over-water. Also, DO NOT apply more than three inches of mulch around trees and shrubs, and keep mulch from directly contacting the base of trunks and stems. Prevent physical damage (e.g., lawnmower injury) that can provide entry points for root/crown rot pathogens. Finally, minimize movement of root/crown rot fungi in your garden. DO NOT move soil or plants from areas where plants are having root/crown rot problems. DO NOT water plants with water contaminated with soil (and thus potentially with root/crown rot fungi). After working with plants with root/crown rot, disinfest tools and footwear with a 10% bleach solution, a detergent solution, or alcohol.

For more information on root/crown rots:
See UW-Extension Bulletin A2532, or contact your county Extension agent.

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4. Bacterial Soft Rot

Hosta damaged by Bacterial Soft Rot

Bacterial Soft Rot can destroy the plant. As you can see from the picture, the center of the crown is rotten, and the plant will not recover after that.

Like most diseases, the pathogens of Bacterial Soft Rot are in the ground and waiting for the right moment to develop. Most often, the infection occurs if in winter hostas are damaged by heavy frosts, and in the spring, the wounds have not yet healed. Through these damages, bacteria penetrate the plant and infect it.

Often the infection occurs during the dividing of the rhizome. If you separate hostas and do not follow all the requirements of sterility, then there is a high risk of infection.

The bacteria of this disease can infect a plant and not show up for some time. When favorable conditions come, the disease begins to develop and destroy the plant. Favorable conditions are high humidity and warm air temperature (above 80 ° F).

Symptoms of the disease are yellowing of the leaves, and the petioles become soft and lie down on the ground. The center of the crown becomes watery and soft.

The peculiarity of this disease is the specific dead fish smell.

If the plant was hit very badly, then it will not be possible to save it. However, if you find the disease initially, there is a chance that the plant will survive.

First, dig hosta out of the ground. Clean it and wash it with water. With a sterile knife, remove all damaged parts of the plant. Put it in the shade for a few hours. Next, place the plant in an aqueous fungicide solution (Phyton 35), let the plant be saturated with the solution.

Transplant hosta to a new location or pot. Use only clean soil.

How to Prevent Asparagus Diseases

When it comes to preventing and treating asparagus diseases, it’s important to act early and often. Proper watering and ample amounts of air circulation are doubly important to make sure your plants don’t suffer from any life-threatening illnesses.

Even if you take all the proper preventative measures, though, it is still possible for your plants to suffer at some stage in their life. After all, asparagus plants live quite a long time – several decades, in some cases – so some hardship is inevitable.

Again, treating your plants early is essential. There are various fungicides you can use to control many fungal diseases.

Otherwise, follow the tips above for preventing and treating each disease and you’ll be able to enjoy a bumper crop of tasty, tender shoots for years to come.

Watch the video: ROOT ROT? Identifying, treating, and preventing houseplant disease