Fungal diseases are difficult to control, and badly infected plants should be removed and destroyed to prevent spread. If you catch the problem before it advances, prune out damaged plant parts and dispose of them in a covered container, and then rake up plant debris around the plant to prevent the fungi from spreading.
Humid conditions are often responsible for fungal diseases. To prevent disease, water plants deeply to a depth of about 6 inches, and let the top 1 inch of soil dry before watering again. Water at the base of the plants to keep the foliage dry.
Provide plenty of air circulation and don't crowd the plants. Be sure petunias are planted in well-drained soil, or in a container with a drainage hole in the bottom.
Viruses can affect a petunia's foliage in several ways, including yellow, distorted leaves as well as giving it a mottled, streaked or spotted appearance. Control of aphids is important because some viruses are transmitted by the pests. Most viral diseases can't be controlled, and the best course of action is to dispose of the plants and start again with fresh plants in virus-free soil.
Fungal diseases are one type of disease that can cause petunias to turn yellow and ultimately die. Petunias can get fungal infections from overwatering which can cause root and stem rot.
Verticillium wilt is another type of fungal infection that causes petunias to yellow. If you have a few plants that have a fungal disease, you have to remove them from the rest of the plants otherwise it will spread to all the other plants and ultimately kill them all.
Make sure you dig out all of the roots of the diseased plants when you remove them. Sometimes humidity or overcrowding can be the cause of fungal diseases. Always make sure there is room in between your plants for air to circulate. The other type of disease that can affect petunias is viral disease. The most common one is Tobacco Mosaic Virus.
Tobacco is bad for humans, but it is also bad for some plants. It is spread through aphids and contaminated soil but also from the hands of a smoker. This virus causes the leaves to turn a mottled yellow and it deforms the leaves and the flowers. If you are a smoker, scrub your hands before working in the garden. Aphids can spread Tobacco Mosaic Virus from plant to plant but can also wreak havoc from feeding on the plant.
They will turn the leaves yellow and cause their growth to be stunted. The best way to treat an aphid infestation is a mix of water and insecticidal soap. Spray it on when the sun is not on the plants and the temperature is below 90 degrees Fahrenheit. Petunias are a pretty and easy to manage addition to any garden or container garden.
Signup Login Toggle navigation. Question by lehleringe August 24, Answer from NGA August 24, You must be signed in before you can post questions or answers. Click here to join! Member Login: Username or email:. Pinterest Facebook Youtube Twitter Instagram. My potted petunias have been beautiful all summer until recently when the leaves started to turn yellow and die from the bottom up. While the leaves were turning yellow, the plants were still flowering nicely. What is causing this?
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