Fire blight is a common disease of plants in the rose family caused by the bacterium Erwinia amylovora. Apple, crabapple, pear, fire thorn, hawthorn, and quince are some of the most susceptible species. Symptoms first appear in the spring as new shoots turn black and bend downward forming a "shepherd's crook". Leaves droop and turn a dark color. Individual branches may look like they were scorched by fire.
Cool and wet weather conditions in the spring are favorable for anthracnose fungi. Symptoms of ash anthracnose are beginning to appear. Infected leaflets often fall to the ground prematurely. A close look at the leaflets will reveal brown to black blotches. These spots commonly start at the margin and develop to the midvein. The leaflets tend to curl around the affected areas, causing a distorted appearance.
Images of ash anthracnose symptoms can be found on the Plant Disease Clinic website :
Sooty mold fungi cause needles, branches, or leaves of trees or shrubs to appear black. The common name "sooty mold" is descriptive of the black coating or crust that is formed on these plant surfaces.
Several different species of fungi often exist together to cause the sooty appearance. These fungi don't infect plants, but grow on the sugary honeydew excreted by aphids, scales, mealybugs, and other insects.
The growth of these fungi is primarily an aesthetic problem, although they can be detrimental to plant health by blocking sunlight and interfering with photosynthesis.
Black spot of rose, also known as leaf blotch, and leaf spot, is a disease caused by a fungus called Diplocarpon rosae. The optimal conditions for disease development are 75-85 F and high relative humidity. Infection may be greatest on leaves that remain wet for six hours or longer. Leaves and canes can become infected.
Are you taking more time getting from one place to the next rather than making a beeline to the warmth of shelter? There is a lot to see outside this time of year. Black knot is one of the curiosities that some people are taking notice of lately. Several examples of this disease were submitted to the ISU Plant Disease Clinic over the past few weeks.
Botrytis blight, also called tulip fire, is the most common disease problem on tulip. Damp, overcast weather favors the growth of the causal fungus, Botrytis tulipae. This fungus commonly attacks tulips that have been damaged by frost or hail.
Tar spot is a fungal disease that doesn't require a fancy microscope for diagnosis. As you might guess, the disease is characterized by raised, black spots on leaves. Tar spot occurs primarily on silver maple.
Early infections appear as yellowish spots on the upper leaf surface. Later in the summer, black tar-like spots form and may be one-half inch in diameter. These black spots have a ridged appearance if examined closely. The undersides of the leaves appear cupped directly beneath the tar spots.
Raspberries are a favorite of many home gardeners. The fruit can be eaten fresh or processed into jam, jelly, or juice. Surplus fruit can also be frozen.
To obtain maximum yields, raspberries must be pruned properly. Appropriate pruning procedures are based on the growth and fruiting characteristics of the plants.
Raspberries have unique growth and fruiting characteristics. The plant's roots and crown are perennial, while the stems or canes are biennial. A raspberry plant may survive and produce fruit for many years. However, the individual canes live only two growing seasons and then die.