How to Grow Young Lemon Trees for High Yields? A Detailed Guide to Cultivation Techniques
Among the countries and regions that produce citrus worldwide, quite a few cultivate lemons. Lemon is a type of citrus widely welcomed by consumers. It is rich in nutrients, containing a good amount of citric acid, vitamin C, vitamin B, vitamin P and other vitamins; the acid content in lemon juice reaches as high as 6%-7%. In addition, lemon also contains various mineral elements such as calcium, iron and magnesium, which are beneficial to human health.
I. Growth Characteristics of Lemon Branches and Shoots Lemon has strong growth vigor, producing 3-5 flushes of new shoots a year, with repeated shooting, flowering and fruiting; the shoots are long and sturdy, giving good yields.
Spring shoots, February to April: the time of new shoot sprouting is relatively uniform, and the number is large; the shoots are short, fine, dense and neat, most of them differentiating flower buds and forming fruiting mother branches.
Summer shoots, May to July: the branches grow vigorously, with strong growth vigor and greater nutrient uptake, dark green leaves and a triangular cross-section, and are prone to forming water shoots.
Autumn shoots, August to October: most are fruiting mother branches for the following year; affected by flowering and fruiting, they sprout in smaller numbers, and the branches are slender and not fully developed.
Winter shoots, November to January of the following year: affected by low temperature and nutrients, they sprout in small numbers and are nutrient-deficient, and are prone to yellowing.
II. Pruning of Lemon Young trees and newly fruiting trees are pruned mainly to build the framework of the canopy so as to expand the canopy faster and better. Young trees are best pruned in winter; during the growing season, pinching and necessary heading back should be carried out, retaining as many branches, leaves and auxiliary branches as possible. Pruning points:
1. Pinching long shoots Young trees tend to produce long shoots. After the shoots of each season emerge, except for retaining 8-10 leaves on long shoots before pinching, all the rest should be pinched as tender shoots. Retaining a length of 20-25 cm is appropriate, to build a substantial and sturdy canopy, branch early and branch abundantly, thereby expanding the canopy as quickly as possible.
2. Promptly remove water shoots Water shoots disrupt the tree shape and waste nutrients, so they should be removed promptly.
3. Branch bending For upright shoots with vigorous growth, the methods of bending and propping are appropriate. Stronger branches should be pulled down, and the branching angle propped open to 40°-50°. Applying bending and propping measures to young trees can bring them into fruiting 1-2 years earlier.
4. Bud rubbing and shoot release For young trees, bud rubbing and shoot release can be carried out in summer, that is, releasing one flush of autumn shoots, to help expand the canopy as quickly as possible.
5. Summer shoot pruning In vigorously growing young trees, many strong shoots emerge. Because strong-growing summer shoots do not readily produce autumn shoots and are also unfavorable for flower bud differentiation, bud rubbing and thinning are carried out from May to July. Therefore, all are cut off in early August, so that more autumn shoots emerge from late August to early September. Most of these autumn shoots flower and fruit the following year.
6. Cultivation of auxiliary branches Small branches that usually emerge within the canopy should generally all be retained, as long as they are not water shoots or excessively dense branches. These small branches are often good fruiting mother branches for young trees.
7. Flower and bud thinning For flower buds and fruits that appear on weak young trees before the planned fruit production, they should be thinned promptly, to promote the tree's nutrient production and quickly form a fruiting canopy and come into production.
III. Measures to Preserve Flowers and Fruits in Lemon After the spring buds emerge, first apply 0.2% zinc sulfate once; before flowering, spray 0.5% urea + 0.2% superphosphate + 1% potassium sulfate once; after two-thirds of the flowers have fallen, or after flowering, spray 0.4%-0.5% urea + 0.2%-0.3% monopotassium phosphate together with a flower-and-fruit-preserving agent (Sanxiao Green Leaf Spirit); during the fruit enlargement period, spray 0.3% urea + 3% superphosphate + 0.5% potassium sulfate. After the young fruits have set well, keep the soil moisture sufficient; the key is to water thoroughly once 10 days before the start of spring.
IV. Fertilization of Lemon The purpose of fertilizing young trees that have not yet fruited is to promote the rapid growth of the canopy and bring them into production as early as possible. However, care should be taken to prevent excessive fertilization that causes over-nutrition and excessive vegetative growth, so that flowering and fruiting are delayed. For fertilizing young trees, the principle of "frequent application, light application" should be mastered. Young fruit trees are mainly fertilized three times a year:
The first fertilization is in mid-February, that is, the pre-flowering fertilizer, accounting for 25% of the year's total; per mu, 800-1600 kg of farmyard manure, 8 kg of urea, 8-16 kg of superphosphate and 8-16 kg of compound fertilizer should be applied.
The second fertilization is from the end of June to early July, accounting for 50% of the year's total; per mu, 1600-3200 kg of farmyard manure, 16 kg of urea, 16-32 kg of superphosphate and 8-10 kg of compound fertilizer should be applied.
The third fertilization is from the end of August to early September, accounting for 25% of the year's total; per mu, 800-1600 kg of farmyard manure, 8 kg of urea, 8-16 kg of superphosphate and 8-16 kg of compound fertilizer should be applied.
V. Pest and Disease Control Integrated methods such as agricultural control, biological control and chemical control are used to keep sources of disease and pests at the lowest level.
Agricultural control: apply more farmyard manure to enhance the tree's resistance; frequently remove weeds to keep the orchard clean and eliminate pest and disease hosts; frequently prune dead, diseased and pest-infested branches to prevent the spread of pests and diseases.
Biological control: raising chickens, ducks and bees in the orchard has a certain control effect.
Chemical control: give priority to prevention and supplement with treatment; understand the disease situation, grasp the pest situation, identify the right timing and apply the right pesticide. In each major area, pesticide spraying should be carried out in a unified way, and pesticides should be used in rotation.
(1) Diseases
Scab: damages tender leaves, tender branches and young fruits. The lesions on leaves are initially water-soaked, then become waxy yellow and suberized, appearing as conical protrusions; in severe cases they cause leaf distortion and deformity. On the fruit rind, tumor-like protrusions appear; diseased fruits are small, deformed and prone to dropping.
Control methods: (1) Strengthen cultivation management, and in combination with winter pruning remove diseased leaves and burn them in a centralized manner. (2) Spray to protect new shoots; spray to protect young fruits when two-thirds of the flowers have fallen, using 50% carbendazim 1000-fold solution or Dafusheng 800-1000-fold solution.
(2) Pests
1. Mites (red spider mite, yellow spider mite, rust mite): damage leaves, causing them to lose their luster and turn grayish white, leading to leaf drop and withered shoot tips. Yellow spider mite damage causes leaves to become deformed and distorted. Rust mite damage causes the underside of leaves to become yellowish brown or rusty brown, and infested fruits to become dark brown.
Control methods: (1) Spray once in early spring, or apply lime sulfur mixture to the main trunk. (2) Spray 73% propargite 2000-3000-fold solution; or Aiciman 1000-1500-fold solution. To control red spider mite well, the first thing is to grasp "focusing on controlling the central infested trees, with large-area control as a supplement."
2. Citrus leafminer: the larvae tunnel under the epidermis of tender leaves, tender branches and fruits to feed, forming white mines, causing leaves to curl, become brittle and drop; infested fruits are prone to rot.
Control methods: (1) Control summer and autumn shoots, removing tender shoots that are too early, too late and superfluous, cutting off the food chain of the citrus leafminer. (2) Carry out targeted control during the vigorous sprouting of summer shoots and the sprouting period of autumn shoots; there are many pesticides available, and it is best to use them alternately to achieve better efficacy. Spray to protect shoots; spray the first pesticide when the shoot sprouting rate reaches more than 20%, using 20% fenpropathrin, Decis or beta-cypermethrin 1500-2000-fold solution.