Symptoms of black spot disease:

Leaves, petioles, shoots and pedicels may all be damaged, but mainly leaves. Symptoms are divided into two categories: one is the foliar surface in the early stage of onset.

Red-brown to purple-brown spots appear on the surface, which gradually expand into round or amorphous dark black spots, and there are often yellow halo around the spots.

The edge is radial, the diameter of the lesion is about 3- 15 mm, and small black spots are scattered on the lesion in the later stage, that is, the meristematic vesicle disk of the pathogen. serious

When the lower leaves of the plant turn yellow, the leaves fall off early, leading to the death of individual branches, such as rose black spot.

The other is the appearance of brown to dark brown near-circular or irregular wheel-shaped spots on the leaves, on which black mold grows, that is, the disease.

Bacterial conidia. In severe cases, the leaves fall off early, which affects the growth, such as Ulmus pumila black spot.

Prevention and control methods:

1. Strengthen cultivation management, pay attention to shaping and pruning, and have good ventilation.

2. Spraying 50% carbendazim wettable powder 500 7- 10/000 times, or 75% chlorothalonil 500 times, or 80% zineb 500 times, 10 times within 7-/0 days, for 3-4 times in total.