Garlic management has its subtleties, and the technical points must be clearly explained
1. What is the current management focus?
Garlic has now grown 7-9 leaves, and the growth period has entered the late stage of scale bud and flower bud differentiation. This stage is dominated by leaf growth and is a critical period for garlic growth and development. The root system gradually expands and shifts from vertical growth to horizontal growth, root growth strengthens, and the accumulation of nutrients accelerates; this is the period that lays the foundation for the growth of garlic scapes and garlic bulbs. Due to the earlier mother bulb degeneration, together with the long duration of cold spring weather this year and delayed watering and topdressing, the plants show dry tips and physiological dry leaves because of a nutrient gap, with grayish, dull leaf color, weak growth, and a smaller green leaf area than in previous years. Therefore, current management should focus on measures that promote growth.
Specifically, the following should be done: (1) Adapt measures to local conditions and manage by category: for plots with severe soil moisture loss and fertilizer deficiency, water quickly and apply a quick-acting nitrogen and potassium topdressing of 20-40 kg (such as Baonong brand compound fertilizer containing 6% vitality factor, 30% nitrogen, and 6% potassium); afterward, watch the weather and the seedlings, and at intervals of 7-10 days, water during the garlic scape elongation stage and garlic clove swelling stage, with an appropriate amount of topdressing. (2) Spray foliar fertilizer to regulate growth: use foliar fertilizer that increases endogenous hormones. Options include 0.136% Bihu (gibberellin indoleacetic acid brassinolide) at 15000 times dilution and Huafu Ainong fertilizer at 750 times dilution.
2. What are the main measures for balanced fertilization?
Garlic is one of the vegetables that requires more fertilizer and is relatively tolerant of fertilizer. Among the various nutrient elements absorbed by garlic, nitrogen is taken up in the largest amount, followed by potassium, calcium, phosphorus, and magnesium. For every 1600 kg of garlic produced, it needs to absorb 13.4-16.3 kg of nitrogen, 1.9-2.4 kg of phosphorus, 7.1-8.5 kg of potassium, and 1.1-2.1 kg of calcium. After scale bud and flower bud differentiation (that is, the period ahead), garlic enters the peak absorption period of the three major elements in its life cycle; before scape extraction is the peak absorption period of the trace elements iron, manganese, and magnesium; after scape harvest, the absorption of the three major elements and boron reaches another small peak, and zinc absorption reaches its peak. Among the three major element fertilizers, nitrogen deficiency has the greatest impact on yield, followed by phosphorus deficiency, while potassium deficiency has a smaller impact; when all three elements are deficient at the same time, the impact on garlic yield is even greater. In addition, calcium, magnesium, and sulfur are also indispensable elements in the process of garlic growth and development.
Based on the above fertilizer requirement patterns of garlic and in light of actual production, we often apply excessive nitrogen, phosphorus, and potassium fertilizers while neglecting medium and trace element fertilizers, emphasize chemical fertilizers, undervalue organic fertilizers, and neglect biological fertilizers. In future production, organic biological fertilizer should be increased and trace element fertilizers should be applied in combination. Among these, organic biological fertilizer should not only be applied as a base fertilizer but also as a topdressing. For organic biological fertilizer, options include Baonong brand yeast vitality organic fertilizer at 50 kg or Chengde Panfeng enzyme bacteria humic acid fertilizer at 80 kg per mu; for topdressing, Chengde Panfeng brand golden potassium calcium topdressing can be used. For trace element fertilizers, in addition to base application, they should also be sprayed on the leaves together with humic acid foliar fertilizer, with spraying about once every 10 days (such as Huafu Ainong fertilizer at 750 times dilution plus Zhexian brand Heizhuangfeng trace element fertilizer at 300 times dilution). For the application of major element fertilizers, a compound fertilizer with a nitrogen-phosphorus-potassium content ratio of 3:1:3 should be selected (such as Baonong brand compound fertilizer containing 18% nitrogen, 7% phosphorus, and 15% potassium).
3. What should be noted in the prevention and control of garlic pests and diseases?
From the perspective of production, the main garlic pests and diseases at present are garlic leaf blight, viral disease, and underground root maggots.
1. Leaf blight: It mainly damages garlic leaves, and the disease begins at the leaf tip or other parts of the leaf. Initially, small round white spots appear, which later expand into irregular or elliptical gray-white or gray-brown lesions, with black mold-like growth on the upper part. In severe cases, all diseased leaves wither and die, with many small black grains scattered on them. When the damage is severe, the whole plant does not bolt. This disease is caused by infection by Pleospora herbarum of the Ascomycota. The pathogen has strong adaptability to temperature but requires relatively high humidity. Rainfall and high field humidity are necessary conditions for the disease to become epidemic.
Control methods: (1) Seed dressing before sowing. Dress seeds with 50% carbendazim wettable powder at 0.3% of seed weight. (2) After harvest in the field, promptly clean up diseased residual plants and branches and leaves, burn or bury them deeply, and reduce sources of inoculum. (3) Strengthen field management. Fertilize reasonably, plant at a reasonable density, water reasonably, reduce humidity, and enhance plant disease resistance. (4) Carry out chemical control promptly at the early stage of disease onset. Options include 70% thiophanate-methyl (Kaitou) wettable powder at 450 times dilution, or 10% methyl difenoconazole wettable powder at 1500 times dilution, or 30% Jingbo kresoxim-methyl wettable powder at 1800 times dilution, once every 7-10 days, for 2-3 consecutive applications.
2. Viral disease: The aboveground leaves of diseased plants become smaller and show pale yellow chlorotic stripes; the new central leaves become slender and, after emerging, appear as pale yellow chlorotic linear deformed leaves. In severe cases, the plants are obviously stunted. The garlic bulbs of diseased plants are smaller, and the number of garlic cloves is also reduced; fibrous roots are significantly fewer than in healthy plants. In severe cases, the garlic cloves become stiff, which is more obvious during storage. This disease is transmitted by virus carried in the bulbs. Due to years of asexual reproduction and transmission by aphids, viral disease is relatively common.
Control measures: (1) Strictly select seed and, according to local conditions, establish a breeding system and base for stock seed and production seed. (2) During the aphid migration season, promptly spray 10% imidacloprid wettable powder at 1500 times dilution, or 50% acetamiprid (Wanxin) water-dispersible granules at 2500 times dilution, to kill aphids and reduce the chance of virus transmission. (3) Where conditions permit, virus-free seedlings can also be cultivated by shoot-tip tissue culture. Use virus-free garlic seed. (4) Spray immunity-inducing fungicides at an early stage: 0.5% amino-oligosaccharin at 500 times dilution or 0.136% gibberellin indoleacetic acid brassinolide (Bihu) at 15000 times dilution. After symptoms appear, it is also possible to spray Lvyeshen at 120 times dilution, 6.5% junduqing (Anfu) at 200 times dilution, or 20% oxadixyl morpholine guanidine (Kaier) at 750 times dilution, which has a clear effect on inactivating the virus and promoting growth.