Selection of seeds

Imported alfalfa varieties are introduced, these varieties have higher yield and quality and are suitable for planting in plots with sufficient water and fertilizer and better soil quality, but they have strict requirements for climate and growing environment. The seeds should be cleaned and dried so that the purity of the seeds reaches 90%.

Fixing the ground

Alfalfa seeds are fine, the young shoots are weak, and the topsoil force is poor, so the fixing of the ground must be fine, requiring the ground to be level, the soil is fine, no weeds, and the moisture is good. Alfalfa root system is developed, deep into the soil, the sowing land should be deep turning, in order to make the roots fully developed.

Fertilizing

Organic fertilizer 1500~2500 kg per mu, calcium superphosphate 20~30 kg as the bottom fertilizer. For the soil fertility is low, sowing and then apply ammonium nitrate and other fast-acting nitrogen fertilizer to promote seedling growth. Each time after mowing to carry out follow-up fertilizer, per mu need 10~20 kg of calcium superphosphate or 4~6 kg of diammonium phosphate. Sowing

The seeds should be sun-dried for 2~3 days before sowing to break the dormancy and improve the germination rate and seedling neatness.

Inoculation

When sowing seeds in land that has never been planted with alfalfa, it is necessary to inoculate alfalfa rhizobacteria, use 5 grams of fungus per kilogram of seed to make a fungus solution sprinkled on the seed, mix it thoroughly, and mix it with sowing.

Sowing period

Spring, summer and fall sowing can be, spring sowing March to May should pay attention to weed removal. Summer sowing often have high temperature burns, affecting seedling growth. Fall sowing in September is the best.

Sowing method

Alfalfa sowing is generally used in strip sowing or ridge sowing, strip sowing row spacing 30~60 cm. Rouge sowing is used in dense ridge sparse planting, row spacing 15~20 cm, both to increase coverage, improve yield, but also to facilitate field management. The amount of seed used per mu is 0.75~1.00 kg, and the amount of seed sown can be increased or decreased according to the quality of seed and different plots. Alfalfa seeds are very small, the depth of mulch is appropriate at about 2 cm. If the soil is loose, pressurize it once before sowing, so that it is easy to grasp the depth; pressurize it again after sowing, which is conducive to moisture conservation. Irrigation and drainage

After sowing, it is necessary to check the seedling in time to ensure that the planting density. Conditional places in the drought can be irrigated, irrigation with furrow irrigation, sprinkler irrigation can be the best sprinkler irrigation. Alfalfa's root system does not tolerate flooding, flooding for 24 hours will cause death, rainy season, low-lying areas should pay attention to timely exclusion of water in the field. Organic fertilizer should be applied before sowing to make the bottom fertilizer, and some phosphorus and potassium fertilizer should be applied appropriately.

Weeding

Alfalfa seedling growth is extremely slow, vulnerable to weed infestation, seedling period, after the return of green, before and after mowing should be weeded. Chemical herbicides are divided into soil treatment herbicides applied before sowing, herbicides applied before seedlings, and herbicides applied after seedlings. However, it should be noted that the drug effect expires 2 to 3 weeks before mowing to avoid livestock poisoning.

Fertilization

Heavy application of phosphorus and potassium fertilizer, generally do not apply nitrogen fertilizer, every mowing, mu of ammonium diammonium 10 kg, potassium sulfate or potassium chloride 15 kg or grass ash 100 kg, or potassium phosphate 5 kg, no need to follow up the application of nitrogen fertilizer.

Mowing

Alfalfa can be mowed 2~3 times a year. The first mowing is most suitable in the early flowering period, when the protein content is the highest. The latest can't be later than the blooming period, otherwise the leaves will fall seriously, the stalks will be fibrous, and the quality will be reduced. Stubble height is generally about 5 cm. The last mowing should be about 30 days before the early frost, and the stubble height should be 7~8 cm to facilitate overwintering. The mowed alfalfa should be shade-dried and timely baled for storage, otherwise over-drying will cause defoliation and affect the quality of grass. Green feeding or sun hay

From the first flower appeared to the whole plant one tenth of the flowering period, the most nutrient-rich grass, stem and leaf yield high and easy to digest, for the best period of harvest, annual harvest 4~6 stubble. Alfalfa mowing stubble height 4 ~ 5 cm, the last harvest should be one month from the first frost, too late for plant roots and rhizome nutrient accumulation.

Grazing

The area should be divided into rotational grazing, every 40~50 days a round of grazing.

Silage

Solitary silage is easy to rot, and can be mixed with grass silage. Common diseases

Alfalfa downy mildew

The frontal surface of the leaf surface appears green spots, irregular shape, no obvious edge, the back of the leaf blade has grayish-white (mauve) frosty mildew, the periphery is yellow, and the leaf blade is more curled downward. Affected plants have twisted stalks, thickened, shortened internodes, and regreening of the whole plant. When spores are produced, the spots become gray-brown and easy to fall off. Alfalfa downy mildew mainly occurs in the Sichuan loess irrigation area and shady and wet areas, the onset of early, starting in late April to early May, generally in early June and the end of July there are two peaks of the disease, the disease basically stops developing in late August.

Alfalfa rust

Victimized leaves first appeared green spots, after the spot slightly elevated sporadic, nearly round or oval, after the rupture of the sporadic spots scattered brownish-red powdery summer spore mounds, leaf crumpling, curling, and even fall off. In severe cases, the stalks can also be infected. Alfalfa rust disease to arid and semi-arid areas as the main occurrence of the place, to the middle and late July to early and mid-August the most prevalent.

Alfalfa powdery mildew

In the early stage of the disease, there is a white mold layer on the leaves, stalks or pods, and then gradually expand, produce conidia, late in the onset of the disease Ban overlays appear gray or light brown closed cysts protozoa, yellow or black dots on the plant growth is poor, easy to drop leaves. Alfalfa powdery mildew occurs from mid to late May to early to mid September, with the most serious onset in arid and semi-arid areas, followed by alpine and humid areas, and occasional occurrences in loess irrigation areas.

Alfalfa brown spot disease

caused by alfalfa pseudomycetes disk, the onset of the initial stem, leaves, pods appear on the dot-shaped light brown green spots, and then expanded to a rounded, mostly in the lower stem, leaves, and then spread to the upper shoot tip leaves. In the later stage, the spots appear as brown disk-like elevations (cysticercus disk), and the leaves turn yellow and fall off. Alfalfa brown spot disease mainly occurs in early June) mid-July.

Alfalfa yellow spot disease

Light brown dots appeared on the victimized leaves at the beginning, and then expanded into green spots, and then turned into large yellow spots. The spots are fan-shaped, stripe-like or round. Diseased leaves dry, early shedding. Later on, many orange-yellow to black cup-shaped dots appear on the diseased tissue, i.e. the cystic disc of the pathogen, mostly on the back of the dead leaves. The onset of time to May-August, mainly harming young alfalfa and the first crop of alfalfa, but alfalfa in alpine shady and wet areas in rainy and low temperature conditions the most serious disease.

Anthrax of alfalfa

Plant stems, leaves, pods are infested, and the rhizome is the most susceptible to the onset of the disease, plant withering, and in severe cases causing death. Plants are small, poor growth, often causing grass to appear bare ground. Disease spot is slightly sunken, the edge is brown, within the edge of the licorice color, bearing many black dots. When the disease is severe, the spots can surround the stem or multiple spots are connected to each other, causing the stem to break. To early June) early September for the peak of the onset of the disease.

Alfalfa root rot

Yellowing of leaves in the seedling stage, wilting and collapse of plants; typical symptoms of adult plant disease is that the root cortical tissues to the xylem become yellow to brown, and the edge of the spot on the main root is not clear. Alfalfa root rot disease mainly occurs in alpine shady and humid areas and the Sichuan loess irrigation area of the transient alfalfa, especially in May and August of the low-temperature rain and irrigation, so that alfalfa is very easy to root rot disease, resulting in alfalfa field pieces of dead and bare.

Major pests

Alfalfa aphids

Aphids mainly include pea webless long-tube aphid, alfalfa webless long-tube aphid and alfalfa spotted aphid. The former two species are predominant in the loess irrigation area, and the alfalfa spot aphid is more frequent in the humid mountainous area. The aphids gather on the young stems, leaves, young shoots and flower parts of alfalfa and suck the sap with their stinging mouthparts. The leaves of the infested plants are curled up, the buds and flowers turn yellow and fall off, affecting the growth and development, flowering and fruiting and forage yield, and the plants die in pieces in the field when it happens seriously. The honeydew of aphids often causes moldy leaves, which directly affects the yield and quality of pasture. Aphids mainly occur in the Sichuan loess irrigation area and shady and humid mountainous areas, there are two peaks of occurrence from late May to early mid-June.

Thrips

Thrips are mainly harmful to leaves, buds and flowers. Young alfalfa leaves are sucked by thrips azole appear map-like white spots, resulting in leaf curling to death. The growing points are yellowed and withered, causing the terminal buds to fail to continue to grow and flower. Thrips infestation is most serious during the flowering period, when it feeds inside the flower, scatters pollen, destroys the stigma, absorbs nutrients from the floral apparatus, causes flower drop and pod drop, and causes the seeds to crumple and reduce yields. When the density of the insect population is high, the leaves start to dry up from the edge, like a fire, resulting in the cessation of plant growth. Thrips in alfalfa are infested, especially in the flowering period and near flowering alfalfa field, late April to late August for the peak of the occurrence of the peak period.

Leaf diving fly

Leaf diving fly with larvae to dive in the alfalfa leaf blade in the upper and lower epidermis, scraping and eating the leaf flesh, the side of the food to the inside of the drilling, the amount of food with the increase in the size of the worm and increase, the submerged path by the edge of the leaf began to bend and extend. When the number of larvae on a leaf is large, the submerged paths are interconnected into pieces, causing the leaves to wither. Most of the chlorophyll is destroyed when the leaf is damaged, only the epidermis and leaf veins remain, and in severe cases, all the lower leaves die. The larvae dive into the leaf flesh, causing circling curved paths, and the food scars are white. Adults lay their eggs in leaf tissue and suck the leaf surface, and the feeding channel is mostly nail-hole shaped. Leafminer infestation can reduce the quality of leaves, reduce photosynthetic area and cause defoliation, hindering plant growth, resulting in a decline in grass production and protein content. late March to late May is the most serious period of infestation, and there are spring and fall infestation of the heavier characteristics. The main place of occurrence for the river loess irrigation area, arid semi-arid area and alpine shade wet area less.

Slanty night moth

The larvae of alfalfa night moth mostly feed on leaf flesh on the leaf surface, and then feed from the edge of the leaf blade inward after the second age, forming irregular notches. The larvae also often like to bore the buds, fruits and seeds of the host plant. It usually occurs locally in August and September. As the larvae feed more on leaves, a large number of feeding in a short period of time, sometimes all the leaves of the victimized alfalfa will be eaten up within 1 week, leaving only the stalks.

Countermeasures

Introduction of new varieties

Resistant alfalfa varieties resistant to pest varieties can effectively reduce the pest population density and reduce the infestation of pathogenic bacteria, reduce or avoid the use of pesticides. At the same time on the alfalfa varieties reasonable layout, to prevent the spread of pests and diseases and epidemic, to avoid the same varieties in the same area of larger scale planting. In the introduction of alfalfa seed, to strictly seed quarantine, beware of the introduction of dangerous pests and diseases.

Focus on and strengthen biological control

Effective protection and utilization of natural enemy resources In the control of alfalfa pests and diseases, it is necessary to fully protect and utilize the natural enemies to maintain the ecological balance of alfalfa land. The populations of predator bugs, ladybugs and lacewings on alfalfa have obvious advantages, and have obvious inhibiting effects on pests such as aphids and thrips. Therefore, when taking every control measure, especially pharmaceutical control, the protection of natural enemies should be considered first.

Timely pharmaceutical control

In the production of the above measures are not yet effective, can be targeted to use highly selective biopesticides and efficient, low residue, low toxicity of chemical agents for control. Can also use the protection row baiting method, that is, in the alfalfa field edge to leave a piece of uncut land as a bait band, when the pest migrated to the bait band for pharmaceutical control. The use of highly toxic organophosphorus pesticides, such as dichlorvos, oxalic acid, parathion, etc., is prohibited. Pesticide safety interval standards should be strictly enforced to maximize pasture safety and protect the survival environment of natural enemies.