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Answer 1

 black spot is a plant disease caused by the fungus Diplocarpon rosae. It is the primary cause of rose defoliation in the Midwest. Over time, repeated defoliations can weaken the plant, reducing flowering. Severe defoliations that result in a loss of most of the leaves, and repeatedly occur, predisposes the plant to insect attack, other diseases, winter injury, and even death. Symptoms Roses infected with black spot primarily develop dark spots on the upper leaf surface in the late spring (Figure 1). Some of these spots occasionally develop feathery edges and can expand up to 1/2-inch in diameter. The leaf spots may also have yellow halos surrounding them. With severely infected plants, the leaves may turn yellow prior to leaf drop. In severe cases, the canes may have small purplish spots on the current year’s growth. Disease Cycle The disease cycle typically begins on fallen leaves or canes that were infected the previous season. Rain or sprinkler irrigation splashes fungal spores from infected leaves that were shed the previous year to the plant’s lower leaves. The spores must remain wet for several hours for infection to occur. Symptoms can become visible within 72 hours after infection during warm, wet weather, and a secondary infection cycle can develop within 10 days after the initial infection. The fungus that causes this disease tolerates a wide range of temperatures, and symptoms can continue to develop all season long if moisture is adequate. The fungus overwinters in infected canes and fallen leaves