The damage of rotten roots of fruit trees is very serious, most of the rotten roots are not easy to detect in the early stage, and after the symptoms appear in the upper part of the ground, they take topdressing and spraying prevention and control measures, and the prevention effect is not good. At worst, it causes the tree to weaken and the yield and quality to decrease, and at worst, it causes the plant to die.
Recently, two consecutive typhoons have led to a sharp increase in soil moisture content, citrus root respiration has been affected, and some newly planted seedling fields and open nurseries have also stopped growing due to water accumulation caused by the root rot of seedlings. In view of the rotten root situation of citrus caused by rain and other reasons, we hereby compile a "root protection and rooting" encyclopedia for fruit growers.
The production technology in the process of citrus cultivation is interlocking, and the occurrence of rotten roots is often caused by a variety of factors, and solving the problem needs to be considered from many aspects. For root rot, first check the orchard environment, then check whether there are large or small roots, or both, and finally understand the measures of orchard management. Then, according to different situations, catch the problem.
The main reason
First, the root system of the abundant green fruit tree has not been renewed
Rotten root performance: the root system starves to death and then rots, followed by citrus from green to weak yellowing, exacerbating the rotten root. Generally, capillary roots and small roots rot first.
Cause analysis: Due to the large number of hanging fruits, the nutrients of photosynthetic products such as sugars and amino acids are mostly transported to young fruits, and the root system lacks nutrients.
Solution: If the plant is moderately productive and the tree is strong, then normal management, increase the application of organic matter fertilizer; if it is too productive, the tree potential is weak, when the organic matter fertilizer is re-applied in summer, prune and cut off part of the root system, so as to promote roots, re-root, raise roots, strengthen roots, achieve root renewal and restore root vitality.
2. Citrus yellow dragon disease
Rotten root performance: the downward transport of nutrients in the plant is reduced, the amount of photosynthetic products reaching the root system is small, the root system is hungry, and the root system will die in large quantities in the later stage. After the root rot, the leaves turn yellow on the plant. Plants exhibit symptoms such as uniform yellowing, mottled yellowing, and red-nosed fruit.
Cause analysis: The pathogen of citrus huanglongbing disease multiplies in the cells of the phloem sieve tube, and the pathogen multiplies in the phloem of the branches, which then blocks the sieve tube.
Solution: Timely spraying to control citrus lice in the new shoot stage, cutting down diseased trees, and planting disease-free seedlings in the new area.
3. Improper management
Rotten root performance: water soaking rotten roots, fat rotten roots and herbicide drug damage, etc., causing root hypoxia and necrosis and rot. Some of them appear to have large roots decaying and fewer capillary roots.
Cause analysis: Poor drainage of orchards. Too much chemical fertilizer is applied, or too much local accumulation, or unsused organic fertilizer is applied, or the concentration of decomposed organic fertilizer is too high. Herbicides are applied excessively, or three without herbicides. Excessive circumcision causes nutrients to be distributed to young fruits and the roots starve to death.
Fourth, insect pests are the main trunk of pests
Rotten root performance: root system lack of nutrients and rotten roots, plant leaf vein yellowing, later the whole plant leaves become yellow. Capillary roots and small roots rot first.
Cause analysis: Dried insect pests such as xingtian cattle and a little bat moth are infested, destroying the xylem or phloem, resulting in obstruction of nutrient delivery.
Solution: In the early to peak stages of pest occurrence, spray organophosphorus insecticides or Bacillus thuringiensis around the trunk to prevent insects, and if the larvae are found to be harmful, they are treated with clematis hooks.
Fifth, the main disease
Rotten root manifestations: wounds on the main trunk, infection with foot rot or glue disease, the leaves of the canopy of the plant lose their luster, turn yellow, and the veins of the leaves are golden yellow.
Cause analysis: The pathogen causes the cortex to glue or decay, affecting the transmission function of the phloem part.
Solution: Reduce mechanical damage to the trunk, scrape off the diseased part, apply fungicide, and avoid the spread of germs.
Sixth, the root of unnamed diseases
Rotten root manifestations: Decay begins with the main root near the head of the tree, the root system is rotting through the longitudinal cracks, and the xylem becomes black.
Cause analysis: Seedlings are rooted with bacteria, or infected with unknown pathogens.
Workaround
1) Dig deep drainage ditches, reduce the water level in the field, and remove the accumulated water in time after the rain;
2) Change fertilization habits, apply thin fertilizer more, apply chemical fertilizer in small quantities and many times, and open a long ditch under the canopy drip line to avoid fertilizer accumulation. At the same time, organic fertilizers such as livestock manure should be prepared and decomposed and mixed with soil when applied;
3) Reduce the application of herbicides, reduce the use of herbicides containing excessive heavy metals, and only spray weeds, do not spray to the ground, moderate grass maintenance of the soil environment;
4) According to the age of the tree, properly set the production, do not ring peeling, moderate circumcision to protect the fruit, appropriate fruit thinning, to ensure that the tree is strong and vigorous, the root system has sufficient nutrition.
Citrus root breaking and root promotion technology
Because the citrus root system has a strong ability to self-neglect and renew, after aging or when the environment is unfavorable, it can die on its own and be replaced by new roots that grow. The use of staged root breaking and root promotion treatment for citrus trees can promote the expansion of the root system and the introduction of roots, improve the root ecological environment, help restore the tree momentum, expand the canopy, increase the effective number of branches and total leaves, thereby improving citrus yield and quality, which is a technical measure for citrus to maintain high quality and high yield and stable yield.
Specific measures:
From mid-July to early to mid-August, a strip of trenches is dug on each side of the canopy opposite the canopy, bounded by the canopy drip line.
Ditch length 80 ~ 100 cm, depth of 25 ~ 40 cm, width to be able to cut the root system prevails, in the broken root ditch each plant applied green manure or slag fertilizer 20 kg, urea 0.3 ~ 0.5 kg, calcium superphosphate 0.8 kg, human and animal manure 30 ~ 50 kg, the water into the ditch, and finally cover the soil to fill in.
The diameter of the broken root is less than 2 cm, and the thicker root is cut with a knife and the fire soil is applied to the wound.
From mid-July to mid-August, the external conditions are more suitable for root growth and development, the root system is at the peak of growth, the wound heals rapidly, and a batch of new roots is quickly issued.
In the same way, the root trench was dug once the next year on the other sides of the canopy opposite.