What on earth is the fruit tree lobular disease?

What on earth is the fruit tree lobular disease?

Fruit tree leaflet disease (figure 1) often occurs in recent years, and there is a trend of aggravation. Leaflet disease mainly shows short plants, diseased branches germinate late, wither or die; individual flowers, flowers are very small, can not blossom and bear fruit normally or fruit small deformity. After years of observation, the author found that the leaflet disease of apple trees is not only caused by zinc deficiency, but also by improper pruning of fruit trees.

Fig. 1 whole tree lobular disease

1 nutritional requirements of fruit trees

In the process of growth and development, fruit trees need not only a large number of elements nitrogen, phosphorus and potassium, but also medium trace elements calcium, magnesium, sulfur, boron, iron, zinc, copper, manganese, selenium, molybdenum and silicon. When the tree lacks certain nutrients, it will show symptoms (figure 2) and cannot grow and develop normally. If it is supplemented in time, its symptoms can be greatly relieved and normal growth can be restored.

Fig. 2 main branch lobular disease

However, there are sometimes synergistic or antagonistic effects among various elements, as well as shortening of internodes, narrowing of leaves, yellowing of leaf color, brittleness and hardening of texture, which can not carry out normal photosynthesis. when the disease is serious, the leaf edge coke of diseased branches has one-way antagonism. For example, there is mutual antagonism between potassium and nitrogen, calcium and magnesium, and there is a synergistic effect among nitrogen, calcium and magnesium. The increase of one element will be beneficial to the absorption of the other two elements. On the other hand, there is an one-way antagonism between phosphorus and nitrogen, zinc, potassium, magnesium, calcium, copper and silicon. When there is excess phosphorus in soil, if nitrogen, zinc, potassium, magnesium, calcium, copper and silicon are not increased, the tree will reduce the absorption of nitrogen, zinc, potassium, magnesium, calcium, copper and silicon, showing the symptoms of nitrogen deficiency, zinc, potassium, magnesium, calcium, copper and silicon; zinc deficiency is related to excessive application of phosphate fertilizer.

2 causes of apple lobular disease

2.1 lobular disease caused by zinc deficiency

2.1.1 excessive application of calcium phosphate in soil zinc deficiency will cause zinc in the soil to interact with excess phosphorus, resulting in zinc phosphate precipitation, which can not be absorbed by crops, resulting in obvious symptoms of zinc deficiency in crops; excessive application of alkaline phosphate fertilizers such as calcium magnesium phosphate fertilizer will alkalinize the soil, reduce the availability of zinc and affect the absorption of zinc by crops.

2.1.2 deterioration of soil physical and chemical properties calcium superphosphate contains a large amount of free acid, continuous application will cause soil acidification, calcium magnesium phosphate fertilizer contains 25% to 30% lime, a large amount of application will aggravate the alkalinity of the soil and worsen its physical and chemical properties.

2.1.3 Zinc deficiency in saline-alkali soil zinc in saline-alkali soil is replaced with soluble salt, resulting in water-insoluble salt and precipitation, which affects the absorption of zinc by crops, resulting in zinc deficiency.

2.1.4 Sandy soil zinc deficiency sandy soil itself low content of organic matter, barren soil, lack of various nutrients, coupled with sandy soil fertilizer and water conservation capacity is poor, nutrient infiltration, resulting in soil zinc deficiency.

2.2 lobular disease caused by improper pruning of fruit trees

In the process of winter pruning of fruit trees, due to non-standard operation, excessive pruning of trees or excessive truncation of strong branches often lead to local occurrence of lobular disease.

It is observed that all the leaflets caused by pruning occur at the top of each tree or at the front end of each main branch, and are caused by the large mouth of the shearing saw. Because in the first growing period of the apple tree, the sawing mouth has inhibited the nutrient transport, seriously affected the normal growth of the apple tree, and caused lobules (figure 3).

Fig. 3 lobular disease at late growth stage

3 symptoms and manifestations of zinc deficiency in fruit trees

Fruit trees lack zinc, plant growth is hindered, plants are short, leaves are green, leaflets and deformities often appear at the tip of branches, internodes shorten in clusters, diseased branches sprout later, leaf expansion is inhibited, leaves are narrow and small, leaf color turns yellow, texture becomes brittle and hard, or leaves do not extend and embrace upward, leaves can not carry out normal photosynthesis, and when the disease is serious, the leaf margin of diseased branches is scorched or branches die. Individual flowers, flowers are also very small, petals are incomplete, can not blossom and bear fruit normally or fruit small deformity, drupe, berry pulp has purple spots. (figure 4).

Fig. 4 manifestation of lobular disease in growing season

The lobular disease caused by soil zinc deficiency is often distributed in the whole garden, in rows or in pieces, and in the whole plant; in production, the lobular disease caused by improper operation or overpruning is sporadic and individual branches appear. The spring germination of diseased trees is later than that of healthy trees. After spreading the leaves, the top leaves are clustered and the middle and lower parts of the branches are bald. The internodes of new shoots are short, and diseased branches are easy to die. The flowers are small and the fruit is small and deformed. The old diseased tree is almost full of leaflets, the crown is empty, and the yield is very low.

4 solution

No matter what the cause of lobular disease is, spray it twice at intervals of 7 to 10 days before and after germination with 200 times of micro-force zinc.

4.1 Zinc deficiency in trees caused by soil factors, applying more organic fertilizer, loosening soil and strengthening root activity

(1) spraying zinc before flowering. If fruit trees are found to delay sprouting, they should be sprayed in time with a mixture of 500 times of zinc or 0.2% (mass fraction) zinc sulfate and 0.3% urea. Urea can promote the absorption of zinc.

(2) Zinc fertilizer was applied to roots. Before the apple tree germinates, dig a radiation ditch under the tree and apply 50% zinc sulfate powder 1 to 1.5 kg, which can be flexibly applied according to the size of the crown. You can also use 700 times of 70% Antaisheng wettable powder. Prevent disease and achieve the purpose of zinc supplement at the same time.

(3) try the method of drip infusion. Each tree is prepared to prepare 2 250 × 500 ml infusion bottles, which are filled with zinc sulfate 500 × 1 000 times. And prepare the medical infusion tube and No. 9 needle. Use a trunk injection machine to drill two small holes, 0.6 cm in diameter, deep into the xylem on the two sides of the trunk of the diseased tree, then insert the needle and tie the medicine bottle upside down to the branch. The effect of each infusion of zinc sulfate solution is about 40 ml, from late April to early May and the prosperous period of new shoots. Pay attention to needle disinfection, infusion should not be too fast, drip 500ml in 24 hours, no fluid outflow is appropriate, after infusion to prevent Rain Water from flowing into the hole, cork can be used. Trees that are rotten and sick should be used carefully in cloudy and rainy days.

4.2 lobular disease caused by improper pruning

It should be pruned reasonably according to the tree conditions, and the combination of weight and weight should be just right. So that the tree structure is reasonable, ventilated and transparent, tangible immortal, invisible and chaotic. The branch collocation is reasonable, the combination of long, medium and short branches, and collocation according to a certain proportion. Winter pruning tries to avoid frost damage. At the same time, do not cause too many wounds in the same branch.