Why do apricot trees have black spots?

Apricot is a kind of deciduous tree. the fruit on apricot is not only delicious, but also its branches, seeds and leaves have different functions. Although it is an important economic fruit tree, it will encounter different problems in the process of planting. Why does apricot tree have black spot?

First, why apricot trees have black spots

Apricot trees with black spots may be infected with scab, which is a fungal disease, fruit infection, mostly in the pericarp part of the primary dark green round spots, facing the fruit expansion and maturity, disease spot expansion, color deepening, serious disease spot aggregation, pericarp cracking.

What is apricot scab

The disease is widely distributed and common in northern China, mainly harming fruits, but also shoots and leaves. Fruit infected, mostly in the shoulder part of the pericarp part of the primary dark green round spots, with the expansion of the fruit, the disease spot enlarged, the color deepened, and then gradually changed to brown and purplish red. When the fruit surface turns yellow and the fruit is nearly ripe, purple-black or red-black mildew spots appear on the disease spot, and when the disease spot is serious, the disease spot aggregates, and the fruit surface is rough, forming cracks.

On the mature fruit, the disease spot is flaky, grayish brown, the pericarp is irregularly cracked and glue flow occurs.

Branch tip infection, first produced oval light brown spots in the diseased part, the edge of purple-brown, and then turned dark brown, slightly raised, the surface dense black particles, several disease spots, can make the upper branches of the plant withered. When the leaves are damaged, irregular or polygonal gray-green disease spots appear between the veins on the back of the leaves, which gradually expand and become brown or purplish red, the disease parts dry up, form perforations, and cause early defoliation in severe cases.

The disease was originally called Cladosporium frutescens, a subphylum fungus. The pathogen overwintered with mycelium on the disease spot of apricot branches in the same year, and produced conidia from April to May next year, which were re-infected by wind and rain. The incubation period of the disease is long, and the primary infection is the most harmful to apricot trees. The germ tubes produced by conidia germination can directly penetrate the cuticular layer of the host epidermis and invade. The first onset of the disease is in May, and the peak period is from June to August. Rain Water's more spring and early summer, low-lying and humid orchards, closed canopies and branches, poor ventilation and light transmission conditions are conducive to the serious occurrence of the disease.

III. Control measures of apricot scab

1. Combined with winter pruning, timely removal of diseased branches, diseased shoots, stiff fruits and other diseased plants in the tree and garden, take out of the garden and concentrated burning, reduce the source of primary infection.

two。 Increase the application of fully fermented mature organic fertilizer or organic-inorganic biological compound fertilizer containing humic acid, and apply fertilizer according to the law of apricot growth to enhance plant disease resistance.

3. Spray 5 Baomedo stone sulfur mixture or 21% peracetic acid water agent 300 times before flower bud germination in spring.

4. Chemical spray control every half a month after falling flowers:

(1) 21% peroxyacetic acid 375 times solution + 80% Dingjia (full complex mancozeb) wettable powder 900 times solution.

(2) 1500 times of 25% pyrimethrin suspension + 3000 times of 25% difenoconazole EC.

(3) 7500 times of 40% flusilazole EC + 75% chlorothalonil wettable powder.

(4) 43% tebuconazole suspension 4500 times + 50% chlorobromoisocyanuric acid wettable powder 750x.

When planting fruit trees, we will inevitably encounter some diseases and insect pests, and we need to take prevention and control measures according to the actual situation.