What are the characteristics of garlic disease outbreaks this year? Key control points explained in one article

Due to long-term drought, in many places this year garlic root development before the New Year was poor, garlic seedlings had weak cold resistance, and the severity of various diseases was greater than in previous years. The author recently visited garlic-growing townships such as Cangshan, Jinxiang and Shanghe in Shandong, and concluded that current garlic production should focus on controlling the following four major diseases:

1. Garlic viral disease. In past garlic production, garlic viral disease was ignored by many garlic farmers. This year, due to the drought weather in the earlier period, the severity of garlic viral disease in some areas was more serious than in previous years. At the early stage of the disease, intermittent yellow dot spots appear along the leaf veins, later becoming yellow-green alternating stripes; the plant becomes dwarfed, and the heart leaf is wrapped by adjacent leaves, showing curled deformity and unable to extend. Sometimes yellow-white and green alternating striped patches appear on the leaves, and sometimes the whole plant becomes yellowed and stunted; when the stem is affected, the internodes shorten. Control methods: (1) When harvesting the previous garlic crop, promptly remove diseased residues and burn them in a centralized manner or bury them deeply; (2) Fertilize reasonably and carry out crop rotation. It is recommended to use no-till fertilizer as base fertilizer, or use no-till topdressing fertilizer when topdressing garlic; by using no-till fertilizer or no-till topdressing fertilizer, soil compaction can be broken, the soil can be loosened, which is beneficial to garlic root growth, makes garlic seedlings complete and strong, and improves virus resistance; (3) Chemical control: at the early stage of the disease, spray 20% Bingdu Kexing 400-fold solution plus 4000-fold solution Shuofeng 481; alternatively, use 1.5% Zhibingling emulsifiable concentrate 1000-fold solution plus 3000-fold solution Shuofeng 481 and 800-fold solution Gaoneng Hongjia, once every 6~7 days, spraying 3~4 times consecutively.

2. Garlic blight. Blight is a major disease of garlic. In continuous cropping plots, heavy clay, poorly drained, waterlogged-prone plots, and plots with excessively high planting density, together with continuous rainy weather, the disease is severe. Garlic blight occurs almost every year in various places, and once infected, it can reduce yield by 30%~40%. Blight generally occurs more severely in rainy summer years. Blight not only damages leaves, but can also damage roots, stems and garlic scapes, with the pseudostem and bulbs suffering the most severe damage. At the early stage of the disease, symptoms first appear at the leaf tip or the middle of the leaf, initially as dark green water-soaked lesions; when they expand to about half of the leaf, the whole leaf turns yellow, droops and soft-rots. When the air is humid, sparse white mold grows on the diseased area. Control methods: (1) When applying base fertilizer, appropriately increase organic fertilizer; combined with organic fertilizer, use 80 kg of no-deep-plowing compound fertilizer per mu; during the garlic greening and seedling-promoting stage, apply 25~30 kg of no-till topdressing fertilizer per mu with irrigation, so that the soil is loose and breathable and surface water accumulation is reduced; (2) Chemical control: use Bangjiawei 500-fold solution plus 4000-fold solution Shuofeng 481; or use 72.2% propamocarb hydrochloride aqueous solution 800-fold solution plus 4000-fold solution Shuofeng 481, spray once every 7 days, spraying 2 times consecutively.

3. Garlic rust. It mainly damages leaves and pseudostems. The diseased area first shows elliptical chlorotic spots, then round or elliptical slightly raised urediniospore pustules appear under the epidermis; after the epidermis ruptures, orange-yellow powdery material is released, namely urediniospores; there is a yellow halo around the lesions. When the disease is severe, the lesions merge and cause the whole leaf to yellow and wither, and the plant dies prematurely; later, on unruptured urediniospore pustules, black telia that do not rupture the epidermis are produced. Control methods: (1) Choose disease-resistant varieties. For example, choose purple-skinned garlic, and avoid mixed planting of scallions and garlic; (2) Pay attention to cleaning the field to reduce the initial infection source; (3) Sow late at the appropriate time, prevent late-stage nutrient deficiency, avoid excessive application of nitrogen fertilizer, reduce the number of irrigations, and eliminate flooding irrigation; (4) Chemical control: choose Bangjiawei 400~600-fold solution plus 4000-fold solution Shuofeng 481; alternatively, use Puxing (25% triadimefon wettable powder) 1000~1500-fold solution plus 4000-fold solution Shuofeng 481 for foliar spraying, once every 7~10 days, spraying 2 times consecutively.

4. Garlic leaf blight. Garlic leaf blight is one of the major diseases of garlic and occurs in all garlic-producing areas. If not controlled in time, it can cause a yield reduction of 50%~80%. It mainly damages leaves or flower stalks. When leaves are infected, small round white spots first appear, then expand into striped to elliptical gray-white or gray-brown lesions, on which black mold grows. When the disease is severe, the diseased leaves wither and die. Control methods: (1) Choose flat terrain, deep soil, and soft plow-layer soil for planting garlic. It is recommended to use 80 kg of no-till fertilizer per mu in the base fertilizer, or mix 1~2 kg of no-deep-plowing agent with 100 kg of ordinary compound fertilizer as base fertilizer. During the garlic greening stage, use 30 kg of no-till topdressing fertilizer per mu applied with irrigation water. (2) Chemical control: use Junwei (prochloraz manganese salt) 1000~2000-fold solution plus 4000-fold solution Shuofeng 481 per mu for foliar spraying; alternatively, use 20% difenoconazole-prochloraz microemulsion 2500~3500-fold solution plus Gaoneng Hongjia 800-fold solution for foliar spraying, once every 7~10 days, 2~3 times consecutively.