Symptoms and control methods of mildew heart disease in apple

Apple mildew heart disease is also called heart rot, mold rot, red rot, fruit rot and so on. The symptoms are mainly harmful to the fruit, especially the Marshal varieties and Fujin, Luxiang and other important fruit diseases bred by Marshal varieties as parents. There are 2 kinds of symptoms. (1) mildew heart type: mildew of gray-green, gray-white, gray-black and other colors are produced in the ventricle, which is limited to the ventricle. (2) Heart rot type: the pulp in the core area rotts from the ventricle to the outer layer, and in severe cases, it can rot through to the surface of the fruit. The young fruit with bitter rotten pulp and serious disease will fall off in the early stage; the lightly diseased fruit can mature normally, but the ventricle can still occur from the mature period to the harvest.

The mixed infection of many kinds of fungi is mainly caused by Alternaria alternata producing black mold layer, pink monosporium producing pink or pink mold layer, Cephalosporium graminearum, Fusarium oxysporum, Penicillium, pseudo-stem point mold, all belong to semi-knowns subphylum fungi. The dominant species are slightly different in different places, some Alternaria fungi are dominant, but Fusarium oxysporum is very few. In the later stage of storage, Monosporium roseum is the main fungus in the fruit of Golden Crown.

Through the route of transmission, the pathogen overwintered by mycelium in the diseased fruit or necrotic tissue and by spores hidden in the scales of the bud. Various types of spores were produced in the following year, which were transmitted by wind and rain, the spores entered the ventricle from the calyx tube, the pathogen mainly invaded at the flowering stage, and the posterior spores lurked in the core of the fruit. With the development of the fruit, the mold began to proliferate, and the diseased fruit could be seen to fall off in June. But it was mostly in the later stage of fruit growth. Some diseased fruits can not show symptoms until the storage period, causing mildew.

The occurrence of the disease is closely related to climate and variety. Early rainfall, heavy rainfall, humid climate, low-lying orchards, closed canopy, poor ventilation are conducive to the disease. Among all apple varieties, the fruit with a large calyx mouth and a long tube connected to the core of the fruit is susceptible to the disease, while those with a small mouth and a short calyx tube are more resistant to the disease. Marshal varieties Hongxing, Huanong No.1, Marshal, Fujin, Luxiang, Hongguan and other calyx tubes are long, wide and serious; semi-open calyx such as Golden Guan is lighter; Zhuguang closed calyx and short calyx tube show disease resistance.

Prevention and control methods:

The main results are as follows: (1) the disease-resistant varieties were selected in the orchard with serious disease. Such as China Fengxian Red Fuji Apple.

(2) strengthen cultivation management, reasonable pruning, keep the crown ventilated and transparent, pay attention to drainage, and reasonably increase the application of organic fertilizer.

(3) to eliminate the source of primary infection. At the end of autumn and the beginning of winter, diseased fruits, stiff fruits and diseased branches were removed and burned.

(4) strengthen the management of storage period. To develop simple controlled atmosphere storage or cold storage, the temperature of the fruit storage should be kept at 0.5 ℃ and the relative humidity should be about 90%.

(5) Pesticide control. Spray once every half a month before flowering, after flowering and young fruit period. Spray with 1Ru 2v 200 fold Bordeaux solution, or 10% polyoxymycin wettable powder 1200 Mel 1500 times, or 50% isobarbamide wettable powder 1500 times.