0650 GMT August 18, 2019
Just like the oppressive heat, oppressive plant disease happens in summer, affecting all sorts of landscape and vegetable plants, roanoke.com wrote.
Disease is usually pretty easy to spot at this point in the season as it has had time to grow and fester throughout the spring. Most plant diseases are fungal in nature, although viruses can plague plants, as well. Here are some diseases to look out for on your plants and some recommendations on how to treat them.
Cedar apple rust (CAR)
This disease plagues apple trees far and wide. It first becomes evident on the upper part of leaves as little yellow or orange pustules called pycnia, according to Cornell University. After a few months, the disease migrates to the fruit, essentially destroying it.
CAR often develops due to a symbiotic relationship between apple trees and juniper trees, which are commonly called red cedars. Junipers host the fungus that causes the disease. Once the fungus matures, it’s carried on the wind to any apple tree within close proximity.
To control this disease, try to destroy any red cedars near your apple trees. Plant varieties such as Liberty, Ambrosia and Sundance instead. For a list of more trees resistant to CAR, visit extension.org.
Tips of trees with this disease look like they have been burnt by fire. Fire blight attacks members of the Rosaceae (rose) family. It may surprise you to learn that many pome fruits such as apples, pears and raspberries are in this family and suffer from fire blight.
This bacterial infection is passed during the spring when plants are in bloom. Trees that harbor the bacteria are visited by pollinators that pick it up and carry it, unknowingly, to an uninfected tree. Containment efforts must happen in the spring by spraying the blossoms with a plant antibiotic.
Further control happens on the other end of the disease. When the “burnt” limbs make themselves known, prune and burn them as soon as possible to prevent future spreading of the bacteria.
Anthracnose is a common term for fungus that presents as lesions on leaves and eventually turns to holes. It is most commonly seen on cucurbit leaves, and, in particular, cucumbers.
To control anthracnose in a vegetable garden, reach for an organic fungicide like Serenade. Spray early and often to prevent anthracnose from establishing itself on your veggie plants.
This fungal disease is found on roses in the heat of summer. It’s typically mild and mostly just unsightly. However, if left unchecked, black spot will kill leaves. If a plant loses enough leaves, it won’t be able to photosynthesize and make its own food.
Fight black spot with neem oil. This organic oil is great for mild diseases and has the bonus of being an insecticide for chewing pests such as aphids. Because neem is an oil, only apply it in the early morning or late evening to prevent it from heating up and cooking your plants.
Many more summer diseases are out there, most of them fungi. Fungus is brought on by heat and humidity, and we have a lot of both going on right now. However, if you keep a constant vigil for disease in your landscape, you can nip these diseases in the bud.