Detailed Explanation of Key Techniques for Autumn Management of Greenhouse Apricot Trees

I. Soil, Fertilizer and Water Management 1. Apply base fertilizer early. The time for applying base fertilizer to greenhouse apricot trees should be earlier than that for open-field cultivation, preferably between late summer and early autumn. Applying base fertilizer at this time, due to the high soil temperature, coincides with the peak period of apricot root growth, so damaged roots heal easily, which can promote photosynthesis of aboveground leaves and promote flower bud differentiation. The fertilizer should be mainly organic fertilizer, and the application rate should be 20%-30% more than that for open-field cultivation, applying 3000-4000 kg of decomposed organic fertilizer per mu. Soil fertilization can be combined with autumn deep plowing, and the earlier the better. Usually the strip trench fertilization method is used: at the outer edge of the tree canopy projection, use machinery to dig trenches 40-50 cm deep, apply the fertilizer into the trenches, and then cover with soil. After fertilization, irrigate once thoroughly, which helps the soil settle and the release and absorption of nutrients.

2. Apply more green manure. Interplant green manure crops between the apricot tree rows, plow them all under in autumn as base fertilizer, and water immediately afterward; this can also achieve good yield-increasing results.

3. Foliar topdressing. The leaves of greenhouse apricot trees grow for a long time and are prone to premature aging in autumn. While applying base fertilizer early to nourish the roots and improve leaf function, attention should be paid to foliar topdressing to improve leaf quality and function. Generally, for apricot trees cultivated in greenhouses, after the Beginning of Autumn, spray foliar fertilizer once every 10 days or so, for 5-7 consecutive sprays. The fertilizers should mainly be highly active organic liquid fertilizers such as urea, monopotassium phosphate, rare earth micro-fertilizer, amino acid compound fertilizer, and titanium micro-fertilizer, and multiple fertilizers can be used alternately.

4. Timely irrigation and drainage. In the late stage of vegetative growth of greenhouse apricot trees in autumn, timely and appropriate watering is beneficial to the synthesis and accumulation of nutrients and to flower bud formation. Before the soil freezes, water with antifreeze water so the trees can overwinter safely. Since apricot trees are not tolerant of waterlogging, if there is a lot of rain or water accumulation occurs, drainage should be carried out promptly to prevent apricot trees from becoming diseased due to waterlogging.

5. Deep plowing and expanding the tree basin. Autumn plowing should be carried out from August to November before the soil freezes, generally to a depth of about 20 cm. For deep plowing, dig a ring-shaped trench 60 cm deep on the ground vertically below the edge of the tree canopy, or dig strip trenches between rows, with no limit on width. When expanding the tree basin, do not cut thick roots, and topsoil and subsoil should be piled separately. When backfilling, mix the topsoil with rotten leaves, weeds, dead branches or other farmyard manure and place it in the lower half of the trench, and place the original subsoil in the upper half of the trench. For soil with a thin soil layer and poor soil structure, the tree basin should also be expanded according to the extension of the apricot root system.

II. Applying Paclobutrazol To further improve the nutritional quality of the tree body and control vegetative growth during the vigorous growth season of apricot trees. In mid-August, spray 300-500 mg/L paclobutrazol wettable powder on the leaves, once every 10 days, for 4 consecutive sprays, focusing on the underside of the leaves when spraying.

III. Autumn Pruning Because greenhouse apricots have weak light, high temperature and high humidity in the early growth stage, they are prone to excessive vegetative growth, which then affects yield and quality. After fruit harvest, the tree body angle has a relatively stable period, and in production during this period technical measures such as topping, pulling, propping and dragging can be used to fix the tree shape. Branch pulling and angle opening should be carried out in August-September after the branches stop growing.

IV. Disease and Pest Control From August to September, according to actual conditions, spray pesticides at the appropriate time to control diseases and pests. Every 15-20 days, spray 70% thiophanate-methyl wettable powder 1000-fold solution or 50% carbendazim wettable powder 800-fold solution to control apricot bacterial shot hole disease. Fenvalerate 20% emulsifiable concentrate 1000-fold solution can be sprayed to control aphids; dicofol 40% emulsifiable concentrate 1500-fold solution or pyridaben 15% emulsifiable concentrate 1000-fold solution can be sprayed to control red spider mites; fenpropathrin 20% emulsifiable concentrate 1000-fold solution or fenpropathrin 20% emulsifiable concentrate 3000-fold solution can be used to control tent caterpillars and walnut caterpillars. In addition, promptly remove dead branches and fallen leaves to reduce sources of disease and lower the overwintering base of pests.