Verticillium Wilt

Verticillium wilt is caused by six different species of fungus, all of the genus Verticillium.  These six fungi can attack most of the plants and trees that gardeners like to grow, including vegetables, fruits, and ornamental plants. Verticillium fungi spend the winter in plant debris lying on the ground.  Cool, wet weather triggers it to…… Continue reading Verticillium Wilt

Powdery Mildew

Powdery mildew is caused by one of the most common and widely distributed fungi that plague gardens.  The disease can attack a wide range of plants, as it is caused by several species of the order Erysiphales.  A sampling of commonly affected plants includes: Cucumbers.Pumpkins.Squash.Melons.Grapes.Phlox.Peonies.Lilacs.Bluegrass.Fescue. The fungus arrives on the scene in the form of…… Continue reading Powdery Mildew

Pierce’s Disease

Pierce’s disease (PD) is a bacterial disease of grapes named for Newton Pierce, who described the disease in 1892.  The bacterium species is Xylella fastidiosa. Sharpshooter leafhopper A grape plant is infected when insects, particularly sharpshooter leafhoppers, carrying bacteria bite the plant.  Bacteria then take up residence in the vascular tissue of the grape and…… Continue reading Pierce’s Disease

Phytophthora Blight

Phytophthora blight, also known as late blight, is a fungal disease caused by several species of the genus Phytophthora.  Affected plants include: Cucumbers.Squash.Pumpkins.Cantaloupe.Watermelons.Tomatoes.Eggplants.Peppers.Potatoes.Beans. The fungi involved flourish in wet, moderately warm weather.  They spend the winter in infected tubers and plant matter.  The disease is spread by soil and moisture. Symptoms Seedling death.Large dark brown…… Continue reading Phytophthora Blight

Brix: What is It?

Brix is one of those topics that come up fairly frequently in sustainable agriculture.  Simply put, brix is a measure of the sugar content of a plant or other substance. To be more specific, Brix expresses the weight of dissolved sugar as a percentage of the weight of the entire solution.  Pure water has a…… Continue reading Brix: What is It?

Peach Leaf Curl

Peach leaf curl is a common disease caused by the fungus Taphrina deformans.  Besides peaches, susceptible plants include nectarines and almonds. The peach leaf curl fungus spends the winter in the bark and buds of its hosts.  It enters new buds as they begin to swell and open in the spring, spread by rain and…… Continue reading Peach Leaf Curl

Fusarium Wilt

Fusarium wilt is a disease common to the southeastern United States.  It is caused by the fungus Fusarium oxysporum and affects numerous garden plants, including vegetables, small fruits, and flowers.  The most susceptible host species include: Tomatoes.Sweet potatoes.Cucumbers.Watermelons. The disease is spread through infected soil.  Once it is introduced, it is nearly impossible to get…… Continue reading Fusarium Wilt

Fire Blight

Fire blight, found across North America, is a disease to be reckoned with. Caused by the bacterium Erwinia amylovora, this blight affects: Pears.Quinces.Apples.Crabapples.Cane fruits.Roses. The disease is most likely to appear after a mild winter and during a wet spring. Insects transport fire blight bacteria from plant to plant when the hosts are flowering. Symptoms…… Continue reading Fire Blight