Form a good tree crown to reduce diseases and insect pests the annual yield of sweet orange will not decrease in winter tube.

The key to the management of sweet orange fruit trees in winter is to form a good crown for sweet orange fruit trees, achieve high yield in the coming year, and reduce diseases and insect pests. Therefore, the management of sweet orange orchard in winter is very important.

Disease Control of Sweet Orange

First, tree management: 1. Shaping and pruning: tree-oriented, respecting "tree rights", fruiting trees only cut dry and withered branches, serious disease and insect branches (especially curly leaf branches damaged by leaf moths), worthless cross branches, old thorns and yellowing late autumn shoots, especially blood oranges, the top growth is vigorous, and the longer overgrown branches should be cut short, and the fruiting trees should be pruned properly after harvest. Pay attention not to cut off the resulting twigs of the second year, try to retain the middle and lower branches of the crown, cut less and lightly, Dora branches, so that its distribution is reasonable, the branches are uniform, and form a natural happy shape. two。 Flower promotion technology: 0.6% urea solution (that is, 6 taels of urea mixed with 100 jin of water) was sprayed at the beginning of November until February of the following year, spraying once a month for 4 consecutive months, which could effectively promote flower bud differentiation.

Second, fertilizer and water management: 1. Moisture: sweet orange trees have been planted for more than three years. If the soil moisture is high, ditches should be opened to drain water, reduce soil moisture and promote flower bud differentiation. two。 Fertilizer: sweet orange seedlings stop applying chemical nitrogen fertilizer (urea, ammonium bicarbonate) from October to the middle of February of the following year to avoid yellowing of late autumn shoots and breeding diseases and pests, but farm manure such as clear dung water and ash fertilizer should be applied according to tree age. Especially in the hanging fruit orchard, a pre-harvest fertilizer based on organic fertilizer was applied in mid-November, combined with irrigation to resist drought.

Third, disease and pest control: 1. Application of pesticides to control pests: pesticides were applied before the end of October to control pests such as red and yellow spiders and rust wall lice, and completely eliminate the source of overwintering insects; from November to the end of January of the following year, 30 jin of water was sprayed with "stone sulfur mixture" crystals according to 3: 4 (first melted in boiling water), and sweet orange seedlings were evenly sprayed, which can effectively kill red, yellow spiders, rust wall lice, shell insects and other pests. two。 Trunk whitening: this method can prevent frost injury and treat a variety of diseases and insects. "Stone sulfur mixture" crystal 1 jin, salt 1 jin, quicklime 10 jin, water 30, mixed into a paste, smeared on the trunk, main branches and other lower light parts. 3. Hunting and killing "longicorn beetles": check the base of the sweet orange tree trunk. If there are holes and fresh insect droppings, you can use iron wire to remove insect droppings, then use iron hooks to kill insects or use cotton dipped in "dimethoate" or "dichlorvos" to plug wormholes, and then close the holes with yellow mud.

Fourth, cold protection: sweet orange is an evergreen fruit tree, semi-dormant in winter and weak in cold resistance. Therefore, to do a good job of preventing cold and freezing of sweet oranges in winter can not be underestimated. 1. Covering: with the arrival of cold winter, cover the roots of fruit trees with different mulches (such as rice straw, straw, sunshade net, thin waste film, etc.) to prevent night ground temperature radiation, in order to increase the surface temperature of sweet orange roots. two。 Soil cultivation pile pocket: soil cultivation can thicken the soil layer, restrain soil water evaporation, increase soil temperature, and the soil height should not exceed the grafting interface. After the frost period of next spring, the soil should be removed to prevent the root neck from mildew. 3. Pay attention to winter irrigation: if there are irrigation conditions, it should be irrigated in time 3-5 days before the cold wave, the amount of water should be up to 10~15cm in the water storage layer of the tree plate, and should be irrigated at noon when the temperature is high, water should be thoroughly irrigated, drained immediately after irrigation, and ploughed in a timely manner to prevent freezing after irrigation. 4. Smoke: thick frost is easy to freeze sweet oranges, especially after freezing, which will aggravate the freezing damage. Therefore, according to the weather forecast, fumigation can be used to radiate heat, reduce frost, smoke, you can choose husks, sawdust, fallen leaves, straw and so on, 4-6 piles per mu, lit before the coming of low temperature. 5. Spray antisteaming and moisturizing agent: spray antisteaming and moisturizing agent on sweet orange canopy before low temperature. It can restrain the water evaporation of leaves, reduce the heat loss and have the effect of heat preservation.