Apple fruit disease is a physiological disease caused by the lack of boron in the soil. The orchards in mountainous and sandy soils are heavier and the drought years are heavier. Diseases are mainly manifested in the fruits, and can occur from flowering to harvesting. When the disease is severe, it can cause a large number of fruit drop, the yield is reduced, and the quality is deteriorated. Some new shoots, buds and leaves also show symptoms.
Fruit shrinkage symptoms
Dry-spot type: mostly occurred in the young fruit period about half a month after flowering. Initially, near-round brown spots appeared on the shady side of young fruit. The flesh of the diseased spot was translucent with water-stained, yellow mucus on the surface, necrosis of the pulp in the later period, browning to dark brown, and dry shrinkage and depression into dry spots. The disease is small and deformed, and the flesh is hard, rough and juicy. Severely falling fruit often falls off prematurely.
Cork type: symptoms appear from after flowering to before harvest, but occur more often in the late growth stage. In the early stage, watery stains began to appear in the flesh and soon turned brown. The sponges appeared soft and fragile. Afterwards, the cork tissue began to emerge from the base of the tube, spreading along the fruit's heartline and spreading radially between the vascular bundles. The pulp in the corked portion is bitter and inedible. In the young fruit period, the fruit was small and deformed, and it was easy to fall early; when the disease was late, the fruit shape was not obvious, but only slightly uneven. The fruit of the red variety is thicker and colored earlier, dark red and easy to fall off.
Rust-type: mostly appear in susceptible varieties, the main features are along the fruit surface around the fruit handle brown, fine horizontal stripe spot, often cracking in the lesions, but the flesh is not necrotic, but soft, pale and tasteless.
Symptoms of fruit shrinkage on foliage
Blight type: At the beginning of the disease, the top leaves of the new shoots are yellowish, and the petioles and veins are pale red to reddish brown. The entire leaf is distorted, with necrotic spots appearing at the tip and leaf margin, and the phloem and stratified tissue at the tip of the shoot. Black spots of necrosis are produced inside. After expanding, they gradually die from the top of the new shoot and form dead shoots. This symptom often appears in August-September.
The arbuscular type: The shoots on the shoots of spring cannot be developed or die soon after they are unfolded. They die from the tip of the new shoot and die later. Many twigs grow under the dead shoots to form the twigs. Serious death can result in pruning.
Tufty leaf type: In the spring or late summer, the branch shoots cannot grow, and the internodes are very short. Many crunchy, small and thick leaves are produced at the festival and are clustered. In severe conditions, a large number of shoots and buds die, seriously affecting the expansion of the crown and the formation of flower buds, and even can cause major deaths.
Prevention
(1) Reasonable fertilization, organic fertilizer application, soil improvement, deep plowing on barren land, strengthening of soil and water conservation, and timely watering in drought year. A large number of fertilization irrigation during flowering can reduce the incidence.
(2) Boron was added. Apples sprayed 0.5% borax liquor once before flowering, flowering, and after flowering. Combined with Shiji fertilizer, 150-200 grams of borax was applied to each tree. The dosage should not be too much. Water immediately to prevent phytotoxicity.
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