Chrysanthemum leaves turn black. What's going on?

First, reasons

Diseases are often encountered in the process of plant growth, resulting in a variety of problems. Blackening of chrysanthemum leaves is also a disaster caused by the disease, which is caused by black spot.

Cercospora chrysanthemum damaged the leaves of the chrysanthemum and caused its leaves to turn black. In the early stage of the disease, chrysanthemum leaves will show green or purplish brown spots, this spot shape is different, there are round, oval and even irregular, its diameter is five to ten millimeters, very fine, the size and color of spots are related to the variety of chrysanthemum.

When a number of small spots gather together, they will form large spots, and at the end of the disease, the color of the spots will also become light gray, giving rise to many less obvious spots, and the leaves begin to decline from the bottom up, but will not fall off. when the disease is serious, there are only two or three intact green leaves on a chrysanthemum.

II. Prevention and treatment

1. First of all, if you find that the leaves that begin to blacken should be removed immediately, if it is winter, destroy the diseased leaves, do not water or reduce watering when it is cloudy or rainy, do not drench the flowers, and do not let the flowerpot be too wet. New flower soil should be replaced every year.

two。 To control fertilizer, nitrogen, phosphorus and potassium fertilizer should be properly distributed, do not let flowers grow crazy, if there is too much water in the basin, should be discharged in time, so that flowers will thrive and enhance disease resistance and immunity.

3. During this period, you can spray the solution, you can go to the market to buy 75% chlorothalonil, 65% zinc, 1% Bordeaux solution. Spraying once every seven to ten days, only three to four times, can reduce the chances of germs being retained.

4. When buying chrysanthemums, it is best to choose varieties with strong disease resistance, often turn over and change soil, add sand and nutrient soil to the soil, and often wash flowerpots, plants and flower soil. If you want to transplant, you should choose the branches whose leaves are very green without pathological changes.