Pear scab, also known as pear scab disease, pear speck disease, occurs in all pear producing areas and can be diseased from flowering to fruit ripening. It is a major disease in pear production. The disease can infect all the green young tissues on the ground of the pear tree, with the leaves, petioles and fruits being the most affected. In the onset of the leaves, a near-circular or irregular black-green to black mildew appears between the main vein and the branch veins on the back of the leaf, and a pale yellow lesion appears on the corresponding frontal surface. In severe cases, the lesions are connected to each other. The entire leaf back is covered with a layer of black mold. The leaves are yellow and easy to fall off early. Petiole onset, appearing oblong depression lesions, black mold layer, severe petiole darkened, leaves yellow, fall off. The young fruit is infected with a yellowish garden spot on the stalk or fruit surface. After the enlargement, the spot is sunken and the spots are covered with black mold, causing malformation, cracking, and even shedding. At the time of the disease, the disease was spotted, the lesions were sag, yellowish-greenish, and sparsely moldy on the upper surface. The surface was corky and easy to crack. Newly infected disease, oval-shaped pale yellow spots, red leaves, yellow, dry, not easy to fall off.
The pathogenic bacteria of the disease wintered on the diseased bud scales with mycelia and conidia, and spread through rainwater during germination the following spring, causing initial infection of leaves and fruits. The disease began in late April and early May. After entering the rainy season in July and August, the incidence of leaf and fruit was severe. From late August to early September, the incidence of mature fruit is heavy. The conidia formation temperature was 12-20°C and the suitable temperature was 16°C. Precipitation is earlier, rainfall is greater, tree vigor is weaker, terrain is low, canopy closure is closed, ventilation is poor, and the incidence of heavier disease in the previous year, bacteria source is more conducive to the disease heavier.
Control measures:
1. Combine winter scissor to remove diseased diseased leaves, diseased branches, diseased fruits and other diseased plants in a timely manner, centralize destruction, and reduce the source of bacteria. Strengthen fertilizer and water management, rational pruning, and enhance the tree's disease resistance.
2. Spray 5 Baume degree lime sulfur or 50% bromobromoisocyanuric acid wettable powder 750 times before germination to eradicate overwintering bacteria.
3. Spray control after falling: 40% flusilazole cream 7500 times, 12.5% ​​diniconazole wettable powder 3000 times, 50% iprodione suspension 1000 times, 43% tebuconazole suspension 4500 times .
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