How to Grow Citrus? A Detailed Guide to Planting Techniques and Cultivation Management

Organic Cultivation Methods for Citrus
Do you like eating citrus fruits? If so, have you ever thought about trying to grow them yourself? Actually, growing them yourself is not that difficult, so why not take a look at the planting introduction below. An organic citrus orchard must have good environmental conditions, with no air pollution, water pollution or soil pollution. Fruit grown this way is also much better for your health.

 

I. Selection and Maintenance of Environmental Conditions

 

The citrus referred to here includes Ponkan mandarin, tankan mandarin, liucheng (sweet orange), sweet orange, pomelo, Wendan pomelo and all other citrus types. An organic citrus orchard must have good environmental conditions, with no air pollution, water pollution or soil pollution. During cultivation, the approach is to use no chemical fertilizers or chemical pesticides at all, or as little as possible, while making full use of various plant residues, poultry and livestock manure compost, green manure and other unpolluted organic waste from on and off the farm, as well as natural mineral powders and beneficial microorganisms, so as to avoid harming the soil, water resources and ecological environment, to maintain sustainable agricultural production and to provide high-quality, highly safe citrus that is beneficial to human health. The above cultivation method that uses no chemical fertilizers or chemical pesticides at all is called pure organic farming, and the method that uses little chemical fertilizer and chemical pesticide is called quasi-organic farming. However, the small amounts of chemical fertilizer and chemical pesticide in quasi-organic farming are recommended for use after harvest until the flowering period; after fruiting, natural control methods should be adopted, and the product must not contain any chemical pesticide residues. Considering management costs and product quality, quasi-organic farming is still the more feasible approach for citrus.

 

II. Adopt Sward Cultivation and Do Not Use Herbicides

 

Citrus is particularly sensitive to herbicides. After using herbicides, citrus trees easily die or show poor growth, which seriously affects both the yield and quality of citrus. Some nematodes also easily appear in orchards where herbicides have been used. Although applying nematicides can temporarily prevent them, they will continue to recur after the effect wears off, and both leaves and fruit will yellow and drop. After adopting sward cultivation, since most grasses are grasses of the Poaceae family, their roots can not only gradually loosen the orchard soil but also eliminate soil nematodes and pathogens. Later, when fertilizing, simply apply large amounts of organic fertilizer, lime and other soil improvement materials on top of the sward, and they will gradually leach downward and be absorbed by the fruit trees. When adopting sward cultivation, try to remove strongly invasive weeds such as goosegrass, dallisgrass, cocklebur, barnyardgrass, purple nutsedge, skunk vine and wild morning glory, and leave gentle weeds such as broadleaf carpetgrass, bermuda grass and carpet grass, so that earthworms and other beneficial microorganisms and small animals in the soil reproduce naturally. The soil will then gradually become loose, which facilitates fertilizing and the normal growth and nutrient absorption of citrus roots. When the weeds grow too tall, use mechanical cutting as appropriate; do not use any herbicide. If local dwarf bermuda grass is planted throughout, then there is no need to mow at all for the entire year.

 

III. Fertilization and Pest and Disease Control

 

Fertilization and pest and disease control for citrus differ greatly depending on the growth stage. Generally, after harvest, efforts should immediately be made to restore tree vigor, cultivate flower buds and thoroughly control pests and diseases that are relatively difficult to control; during the young fruit stage and mid-fruit stage, the focus is on promoting fruit enlargement and controlling pests and diseases; in the late fruiting stage, efforts should be strengthened to increase fruit sugar content and quality. These are described separately below:

 

1. Fertilization and Pest and Disease Control After Harvest

 

The first task after harvesting citrus is restoring tree vigor, so irrigation and fertilization should be carried out as soon as possible, especially applying an appropriate amount of quick-acting nitrogen fertilizer. Generally, organic liquid fertilizer made from oilseed meals or other quick-acting nitrogen fertilizers such as urea or blood meal can be used. Once there is a little more time, apply complete organic fertilizer and some soil improvement materials containing phosphorus, calcium, magnesium, etc. as base fertilizer. For organic fertilizer, you can choose coarse organic materials, fine organic materials and soil improvement materials, and begin mixing and piling them at least two months before use. The main coarse organic materials include rice hulls, rice straw, bagasse, sawdust, leaves and peat. Fine organic materials include pig manure, cow manure, sheep manure, oilseed meals (soybean meal, peanut meal, sesame meal, rapeseed meal, cottonseed meal, castor bean meal, etc.), rice bran, bone meal, guano or phosphate rock powder, seaweed powder, shrimp and crab shell powder, etc. Soil amendments include dolomite powder, limestone powder, oyster shell powder, magnesia lime, slaked lime, oyster shell ash, zeolite, medical stone, rice husk charcoal, charcoal crumbs, beneficial microorganisms (black sugar enzyme), etc.; the above materials can be selected and used in appropriate amounts according to economic cost and convenience of availability. In addition to adding a small amount (about 3% or less) of soil amendments when making organic fertilizer, they should also be fully applied together as base fertilizer according to soil conditions at the time of base fertilization, and then beneficial microorganisms should be sprayed over the whole area.

 

For pest and disease control, inspect the field. If leaves show obvious yellowing and leaf and fruit drop, it is very likely that nematodes have invaded the roots and caused damage. You can add 10 kg of rice bran, 5 kg of shrimp and crab shell powder, 10 kg of black sugar and 2 liters of comprehensive beneficial microorganisms (black sugar enzyme) to 100 liters of clean water, let it ferment for about half a month, then dilute with water at 50 times, draw it up with a water pump and apply it to the roots through a plastic hose.

 

Much of the yellowing of leaves is caused by nematode damage and can be sprayed with rice bran comprehensive beneficial microorganism sugar water.

 

To prevent the occurrence of some diseases and rust mites, spray with 300-400 times lime sulfur mixture regularly. Spraying in the evening or on cloudy days is less likely to cause phytotoxicity. To prevent scale insects and the like, choose the coldest time in winter to spray once with high-grade summer oil at 100-200 times plus camphor oil at 600-800 times (or citronella oil and peppermint oil at 500 times each) and wood vinegar at 400 times. For weaker trees, high-grade summer oil should be used at higher dilution; for strong trees, lower dilution can be used. At least two weeks should be left between the use of lime sulfur mixture and the use of summer oil. About two months before flowering, begin spraying comprehensive beneficial microorganisms (black sugar enzyme) and brewed vinegar (wood vinegar at 400 times) at 300 times each several times to cultivate flower buds. Within about one week before flowering, if sunlight is poor or the temperature is too low, spray once with boric acid at 1000 times (or additionally add plant-based amino acids at 1000 times) to increase the fruit-setting rate. When new shoots appear, larvae of noctuid moths such as leaf miners (scribble bugs), tussock moths and shrimp-shell hawk moths are likely to cause damage, and synthetic pyrethroids, Bacillus thuringiensis, etc. can be sprayed in appropriate amounts for control.

 

For rust mite damage, pay attention during the fruiting period to spraying lime sulfur mixture or

soluble sulfur powder, especially during May.

 

For scale insects, spray in winter with high-grade summer oil plus camphor oil or

lime sulfur mixture plus citronella oil, neem oil, etc. for control.

 

2. Fertilization and Pest and Disease Control During the Young Fruit Stage

 

During the young fruit stage, the soil should maintain appropriate moisture and be supplied with an appropriate amount of nitrogenous organic liquid fertilizer or other nutrients to promote fruit enlargement. The most convenient method is root irrigation with oilseed meal liquid fertilizer. To make oilseed meal liquid fertilizer, add 6 kg of soybean powder (or rapeseed meal, etc.), 6 kg of rice bran, 1 kg of phosphate rock powder, 2 kg of seaweed powder, 1 liter of animal-based amino acids, 6 eggs, 12 kg of black sugar and 2 liters of comprehensive beneficial microorganisms (black sugar enzyme) to 100 liters of clean water, mix thoroughly, stir once each morning and evening, let it ferment for about 15-30 days, then dilute with water at 50 times and add humic acid at 1000 times or other nutrients, and apply together to the roots. If spraying on the leaves, replace soybean powder with soy milk and replace rice bran with 3 kg of milk powder; there is no need to filter, and it can be sprayed after diluting with water at about 100 times. Ordinarily, spray once about every half month with comprehensive beneficial microorganisms (black sugar enzyme) at 500 times and brewed vinegar at 600 times (or wood vinegar at 800 times). To improve insecticidal and fungicidal effects, before using the brewed vinegar, first soak about 15-20% each of garlic, chili, tobacco leaves, wormwood and fishwort in it. To control fruit flies, when preparing the spray liquid, additionally add citronella oil or peppermint oil at about 800 times for spraying. To control noctuid larvae, additionally add Bacillus thuringiensis for spraying. Others such as fish extract, seaweed extract, amino acids, potassium humate and neem oil can all be selected and added in appropriate amounts to spray together to help fruit growth or control leaf mites, etc. In some orchards with poorer management, rust mites may occur during the young fruit stage, and by the later stage they become black mandarins or black pomelos. If there is a risk of occurrence, spray wettable sulfur powder at 300-400 times as soon as possible.

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4. Fertilization and Pest and Disease Control During the Mid-Fruit Stage

 

After the mid-fruit stage, the orchard gradually enters the hot and humid summer, and pests and diseases gradually become more serious. In addition to strengthening pest and disease control, nitrogenous liquid fertilizer or other nutrients should continue to be supplied to help the fruit continue to grow. However, at this time the nitrogen component should be appropriately reduced according to the growth situation while phosphorus and potassium are appropriately increased. Therefore, when making oilseed meal liquid fertilizer, the high-nitrogen soybean powder can be removed and only the following materials used: 100 liters of clean water, 3 kg of soybean powder, 6 kg of rice bran, 3 kg of phosphate rock powder or guano, 2 kg of seaweed powder, 1 liter of animal-based amino acids, 3 eggs, 10 kg of black sugar and 2 liters of comprehensive beneficial microorganisms (black sugar enzyme). Mix thoroughly, stir once each morning and evening, let it ferment for about 15-30 days, then dilute with water at 50 times and additionally add humic acid at 1000 times or other nutrients, and apply together to the roots. When spraying on leaves, replace soybean powder with soy milk and replace rice bran with condensed milk; after preparation, it can be diluted with water at 100 times and sprayed on the leaves.

 

During the mid-fruit stage, the use of comprehensive beneficial microorganisms (black sugar enzyme), brewed vinegar, wood vinegar and other additives is the same as in the young fruit stage, but brewed vinegar is changed to 400 times and wood vinegar to 600 times. In addition, potassium phosphate at 2000 times, magnesium dihydrogen phosphate at 3000 times and manganese sulfate at 2000 times can be added in appropriate amounts for spraying together. Also, to control black spot disease, canker, scab and green mold, lime Bordeaux mixture at 300-400 times can be sprayed, about once every half month. Start with a higher dilution, and later the dilution may be appropriately lowered according to actual need. To prepare 120 liters of 300-times lime Bordeaux mixture, weigh 400 grams of quicklime and first dissolve it in about 20 liters of clean water, then weigh 400 grams of copper sulfate and dissolve it in 100 liters of clean water. Slowly pour the dissolved copper sulfate water into the quicklime water while stirring and mixing, and then it is ready to spray. Spraying lime Bordeaux mixture should avoid evenings or weather with high air humidity to reduce phytotoxicity. Usually from late spring to early summer, as the temperature gradually rises, rust mite occurrence gradually becomes more serious, and spraying wettable sulfur powder or lime sulfur mixture at 300-400 times should be strengthened. Wettable sulfur powder has a very good effect on controlling rust mites, but a poorer effect on controlling diseases; lime sulfur mixture has a better effect on controlling diseases, but should be used in the evening or on cloudy days to reduce phytotoxicity. In addition, from about May to September is the period when longhorn beetles are more active, and attention should be paid to preventing them from laying eggs on the trunks. Although there are many control methods, a more convenient method is to spray the trunk area with camphor oil at 800 times plus non-toxic soap powder at 1000 times after emulsifying, about once every half month. If they have already entered the trunk, soak cotton in camphor oil, insert it into the hole, and seal the opening with plastic tape.

 

For black spot disease, Bordeaux mixture with neem oil added can be sprayed in appropriate amounts.