Apple Alternaria Leaf Spot Control, Powdery Mildew Prevention, and Apple Tree Canker Treatment
Many farmers have a lot of experience growing apples. As a country with high apple yields, China's apple cultivation techniques have also gained worldwide recognition. The release of various apple varieties onto the market has given consumers more choices. So how much do you know about controlling the pests and diseases that arise in apple cultivation? Tuliuwang has summarized for you the control methods for apple Alternaria leaf spot, preventive measures for apple powdery mildew, and control methods for apple tree canker.
I. Control Methods for Apple Alternaria Leaf Spot
1. Strict quarantine. As far as possible, do not introduce seedlings or scion wood from diseased areas.
2. Strict orchard sanitation. In autumn and winter, carefully sweep up fallen leaves, prune out diseased branches, and burn or bury them in a centralized manner. Before bud break, spray 40% asomate wettable powder at a 100-fold dilution to eliminate the source of the disease.
3. Forecasting and monitoring. A spore trap can be used for monitoring. The method is to coat a glass slide with petroleum jelly, tie it with string and hang it on a branch at 1.3-1.5 m above the ground, hanging 5 slides near the four corners and at the center of each plot, replacing them once every 3 days, and examining the removed slides under a microscope. On the fourth day after the peak spore day, lesions the size of a millet grain can be seen; on the seventh day after the peak day, when the first lesion is found in the field, spraying should begin for control.
4. Chemical control. Focus on protecting the early leaves, with prevention as the foundation. The first spray should be in mid-May, and the second spray 7 days later. Spray once more in mid-June, mid-July and mid-August respectively. Note to alternate among multiple chemicals.
Spraying Plan
Alternaria leaf spot is severe during the spring shoot period (late April to late May) and the autumn shoot period (late June to mid-to-late July); brown spot can occur from June to August, with July to August being the peak period. Practice has proven that spraying to prevent primary infection is very important for controlling later-stage disease.
Generally, the following are adopted: A. For orchards with mild disease in previous years, use "Liang-Guo-An" diluted 200-300 fold and spray; B. For orchards with mild disease in previous years, use "Liang, Guo, An" 300-fold solution + (Wo-Feng-Su) 600-fold solution for spraying; from 7-10 days after flowering all the way to the fruit ripening stage (November), spraying must be maintained once every 10-15 days to protect the leaves and prevent infection.
Focus on protecting spring shoot leaves. According to rainfall conditions, begin spraying 10-15 days after petal fall, spraying 3-5 times, with an interval of 15-20 days each time. Effective chemicals include: 50% iprodione wettable powder or 10% polyoxin 1000-1500-fold solution, 70% fosetyl-aluminum plus mancozeb mixture 800-fold solution, or 70% mancozeb wettable powder 500-fold solution. Specific fungicides for controlling Alternaria leaf spot also include: 10% polyoxin 1000-fold solution, 50% iprodione 1000-fold solution, 10% difenoconazole 4000-fold solution, 0.15% wuningmycin 400-fold solution, 12.5% diniconazole 2000-fold solution, 25% tebuconazole 1000-fold solution. Mixing any one of the above chemicals with the fertilizer-chemical mixture [Guo Bao] can achieve twice the result with half the effort.
II. Preventive Measures for Apple Powdery Mildew
1. Select apple saplings that are disease-resistant, pest-resistant, high-yielding and free of pests and diseases,
2. Select fields with high, dry terrain and convenient drainage and irrigation as the orchard,
3. When disease occurs in the nursery, continuously spray 50% sulfur suspension 200-fold solution, or 0.2-0.3 degree Baume lime sulfur mixture 2-3 times (at intervals of about 7 days) at the early stage of disease onset
4. For bud-grafted saplings, cut the rootstock 15-20 days before bud break, disinfect the wound with 1% copper sulfate, then apply Bordeaux mixture for protection. When planting saplings, it is best to set the graft union level with the ground; avoid planting too deep, and water thoroughly to shorten the recovery period.
5. Before fruit trees bud break, spray once with a mixed chemical for pest and disease control; in combination with the control of other pests and diseases, spray 40% asomate 100-fold solution or 3-5 degree Baume lime sulfur mixture plus 0.3% sodium pentachlorophenate mixture to protect the trunk.
6. When young fruits form, bag them in paper bags coated with perilla oil.
7. In autumn when 50% of the leaves have fallen, spray 1.58% phenylmercury nitrate (PMN)
III. Control Methods for Apple Tree Canker
1. Prune reasonably, thin flowers and fruits. Adopt scientific pruning techniques to form a reasonable tree shape and promote vigorous growth of the fruit tree; at the same time, adopt flower- and fruit-thinning techniques to avoid the formation of alternate bearing and enhance the tree's disease resistance. (2) Strengthen the control of other pests and diseases of the fruit tree.
Strengthen cultivation management: enhance tree vigor and improve the tree's disease resistance.
2. Fertilize reasonably; apply 50 kg of compound fertilizer with a nitrogen:phosphorus:potassium ratio of 7:3:7 to each fruit tree, and increase the application of farmyard manure, pen manure and green manure.
3. Thin flowers and fruits to eliminate the alternate bearing phenomenon.
4. Apply whitewash to prevent freezing injury; in areas prone to sunscald, whitewash the trunk after leaf fall in early winter.
5. Reduce wounds; do not prune in severe winter, and apply paint to wounds.
6. Prevent spring drought and waterlogging, keep the tree's water content normal, reduce the pathogen's ability to expand, and speed up wound healing.