AP BIOLOGY

Detailed explanation-1: -Black spot is caused by the fungus, Diplocarpon rosae. It is one of the most common diseases found everywhere roses are planted. The disease does not kill the plant outright, but over time, the loss of leaves can weaken the plant making it more susceptible to other stresses and winter damage.

Detailed explanation-2: -A Cornell University researcher demonstrated that a mixture developed for powdery mildew-1 tablespoon of baking soda mixed in a gallon of water, with a bit of horticultural oil or liquid soap added to help it cling to the leaves-is also effective for reducing the spread of black spot.

Detailed explanation-3: -Aptly named black spot is a fungus that causes dark spotting on rose leaves and stems. Eventually, leaves turn yellow and drop off before autumn. Spores overwinter on the fallen leaves and re-infect the plant in spring when new foliage appears.

Detailed explanation-4: -The initial symptoms start as feathery-edged, black spots on lower leaves. As these spots enlarge, the leaves turn yellow and drop off. The disease continues up the stems until the entire plant becomes defoliated. Stem lesions are less obvious but start as dark, irregular blotches that eventually become blistered.