Cultivation Giude for Soft-Pod Snow Pea Variety Series

1, Requirement of Circumstance and Conditions

1.1, Temperature

The sow peas belong to the crops which are hemi-resistant to cold. They are more resistant to cold, but not to heat, and are fond of climate which is cold and moist. The starting temperature for sprouting is low, 1-2 degree centigrade for round seeds and 3-5 degree centigrade for wrinkled seeds. But the sprouting will be slow in low temperature. After imbibition of water, the seeds will germinate in 4-6 days under the temperature of 15-18 degree centigrade, and the germinating rate can reach more than 90%. When the temperature is higher than 25 degree, the sprouting time will be shortened by 3-5 days, but the germinating rate will reduces to be about 80%. When the temperature reaches up to 30 degree, the sprouting rate will reduces to below 80%, and the seeds will go rotten easily. The lowest temperature for germination is 8 degree. The snow peas have strongly adaptable to low temperature in the seedling stage, and it is the strongest when the seedlings grow out 5 pieces of compound leaves, to 5-6 degree below zero, even 7-8 degree for some varieties. Along with the growth of compound leaves, the cold resistance will weaken gradually. The suitable temperature for growing period is about 12-20 degree. The plant will be frosted when the temperature is 1 degree below zero. The suitable temperature is about 15-18 degree for blossom, and 18-20 degree for maturity stage. When the temperature is above 26 degree, the factors of high temperature, droughty, strong wind or raining weather, will cause failure in the development of flower organ. The result is that, the fertilization rate will be reduced, the podding quantity will be less, the dropping of flower and number of abnormal pods will increase, and the damage by disease will be serious, causing low quality and yield. If run into low temperature in zero degree, it will reduce the number of blossom, but the flower blossomed usually can bear pod.

1.2, Illumination

The snow pea belongs to the long-day crops. The blossom of most varieties will be advanced when the illumination time is prolonged, and be delayed when the illumination time is shortened. Therefore, it is fond of light in podding stage, and requires stronger illumination and long time of day length, and should avoid high temperature. Under the conditions of long day length and low temperature at the same time, the differentiation node of flower bud will be lower, with more branches. Therefore, when cultivated in Spring, if the sowing time is late, the blossom node will be high and the yield be reduced. But for early maturity variety, it is not sensitive to the time of day length, so it can blossom and podding even when cultivated in Autumn. The differentiation of flower bud will be promoted and the bearing period will be shortened under long-day and low temperature. Therefore, when the variety is introduced from south to north, the blossom and podding will be advanced. For normal variety, it requires strong illumination and long time of day length in podding period. The short illumination will weaken the growth of plant and reduce quantity of podding. The varieties in occident do not require the time of day length strictly. For reverse-season cultivation with protection facility, pay attention to choose suitable varieties.

1.3, Moisture

The snow pea is fond of moisture. It requires moist soil humidity and air in the whole growing period, and is not endurant to drought and waterlogging. For the sprouting of seeds, it has to absorb 1-1.5 times of moisture than the weight of seed. When the moisture of soil is not enough, the germination will be delayed and hardly become trim, but too nuch moisture will easily leads to rotten seed. In seedling stage, it is endurant to drought in some extent, which is very beneficial for development of root. If the humidity is too high, it will easily causes root rot and powdery mildew diseases. The proper relative air humidity is 60%-90% in blossom period. If the air is droughty, the quantity of blossom will be reduced and easily causes dropping of flower and pod. When the relative air humididy is bellow 55% and the absolute water content of soil is lower than 9.7%, it will easily causes dropping of bud and flower. If meeting with high temperature and droughty weather in growing period of pod, the fibre will hardens in advance and the pod will matures too early, which will reduce quality and yield. Therefore in the whole growing period, the supppy of water should be adequate so as to ensure quality and yield. The snow pea is not endurant to waterlogging, if the moisture is too much, it will causes rotten seeds after sowing, rotten root in seedling stage and diseases in growing period.

1.4, Soil and Nutrient

The snow pea has strong adaptability to soil, and the most suitable soil is sandy loam or loam which has well ventilation and is in neutrality or subacidity( PH value is from 6-7.2). This kind of soil will be conducive not only to germination, but also to the growth of root system and rhizobium. When the PH value is lower than 5.5, it easily causes disease and reduce podding rate. Supply lime to adjust the PH value. The secretion of root will impact the growth of root system and rhizobium in the following year, so it is fear of continuous cropping.
 
Athough the snow pea has root nuble for fixing nitrogen, the nitrogen fixation power is week in seedling stage when the root nuble is forming, the nitrogen fertilizer should be supplied, also in blossom and podding period when the growth is vigorous, so as to promote the growth of the plant. The snow pea also needs more phosphate and potash fertilizer. Whe the phosphate fertilizer is not enough, the branches in base node of main stem will be reduced and not grow good, even causes wilting and death. The potash fertilizer can improve the concentration of cell sap, which will enhances cold-tolerance and may promote the sunthesis of protein and thickenning of grain. Generally the requirement of nitrogen, phosphate and potash for growth and development is in the ratio of 4:2:1. In addition, the pea pods is sensitive to boron and molybdenum, which can promote the formation and growth of rhizobia, and play a role in improving the ability of nitrogen fixation. Therefore, attention should be paid in the selection and use of fertilizers in cultivation, in order to facilitate to increase production and quality.

2, Cultivation Season and Selection of Variety

For Sping, it is sown in middle Feb. generally, and harvested and enter market from middle May. For Autumn, it is sown in middle Aug., and harvested and sold to market from middle Oct. It is suggested to choose varieties such as Improved Soft-Pod No. 11 Snow Pea, Holand Short-Grow Soft-Pod Snow Pea, France Short-Grow Soft-Pod Snow Pea, and so on.

3, Preparation of Field and Supply of Base Manure

As the development of taproot of snow pea is early and fast, the field should be prepared carefully and finely, and the base manure should be supplied adequately. For Spring sowing in north areas, as the sowing time is earlier, the fild should be prepared and the manured in Autumn in last year. For each acre, supply 18000-30000kg of quality farmyard manure, 300kg of calcium superphosphate, 90kg of ammonium nitrate, and 300kg of wood ash or 90-120kg of potassium chloride, mix evenly and then manure. Plough the field in 20-25cm depth and then level off to make ridge. In north areas, cultivate on fat ridge in Spring, with width of ridge in 160-200cm for vine-growing variety and 100-150cm for short-growing one. For other season, it is suitable to cultivate on high ridge, so as to prevent the accumilation of water on ridge surface in rainy season.

4, Sowing

4.1, Seed quantity

The seed quantity per acre is about 48-60kg for short-growing variety, and 30-48kg for vine-growing one. the adjustment of seed quantity should according to the kernel weight.

4.2, Planting Distance

Dig ditch before sowing and supply adequate base water. For short-growing variett, dig ditch in 30-45cm of linewidth and sow in raw. For vine-growing variety, dig ditch in 80-100cm of linewidth and sow in hole which is in 10cm of planting distance, each hole with 2-3 grains of seeds and two raws per ridge, then cover with 3-4cm thick soil.

5, Field Management

5.1, Cultivation

After the trim germination of seedling, cultivate in time to increase earth temperature and maintain soil moisture, and to promote the activity of soil microorganism and to control the spreading of weed. From seedling stage to vine-speading stage, cultivate for 2-3 times. If for irrigation, loosen soild in time when the soil surface becomes dry, to prevent soil from hardening.

5.2, Building Shelf and Leading Vine

For vine-growing snow pea, it starts spreading vines when the seelding is about 20-30cm high, the shelf should be built in time for to leaf vines onto shelf artificially. Use thin string to bind vines, to make it ventilated and illuminated, in order to conducive to blossom and podding. Generally take off top when the chief vine outgrows 4-5 nodes, and when the side vine outgrows 2-3 nodes, to promote the germination of side vine, in order to increase flower quantity and podding rate.

5.3, Management of Fertilizer and Water

When sown in Spring, as the earth temperature is low, it is not suitable to irrigate before germinatin and in seedling stage, so as to promote the development of root system. Irrigate slightly when meet with droughty weather. In blossom period, irrigate properly to prevent drought or high moisture from causing dropping of flower and pod. When the pod comes into the expanding period, water should be supplied adequate, but not to make accumulated water in field, and drain in time after heavy rain. The snow pea will get rotten root and early ageing when get waterlogging.
 
If ther is not quick effective nitrogen fertilizer in base manure, supply 90kg of ammonium nitrate per acre. along with cultivation. If the supply of base manure is light, or the phenomenon of fertilizer-lossing appears in late delveloping period, top dressing in vine-spreading and podding period. In vine-spreading period, supply about 90kg of urea per acre. Supply 180kg of compound fertilizer per acre, or spray microelement fertilizer on leaf surface, such as 0.2% monopotassium phosphate, 0.1% borax, or 0.02% ammonium molybdate, 180-270kg of fertilizer liquid per acre, spray 2-3 times totally. This will increase the quality and yield of pod.
 
When come to blossom acme, spray 30×10⁶ of PCPA for control of dropping of flower and pod.

6, Control of Disease and Insect Pest

6.1, Control of Disease

6.1.1, Powdery Mildew Disease
The disease can attack leaf, stem and pod, mainly by leaf. The disease spot on front side of leaf is in lighe-yellow color at first, and then spreads gradualy to be irregular white powder spot. And the back side of the spot is in brown or purple-brown color. The surface of the disease part is coverd by white powder. the leaf and stem will yellow and the tender stem will dry-shrink when the serious. In late period, the cleistothecium will outgrows from the layer of white powder, in yellow color at first and then turn into black dot. This disease usually appears in blossom and podding period, maily from leaf in low layer and then spread upwards. The occurance and prevalence of this disease have much relations to climate and the resistibility of variety. Warm daytime and cold night, rainy and humid environment are more conducive to the disease, but in droughty weather, the disease can still outbreak seriously.
Control method.
 
A, Select disease-resistant variety accoring to circumstance.
 
B, Seed disinfection. Dress seed by 70% thiophanate methyl WP in the 0.3% weight of seeds. Or use 50% carbendazim and 75% chlorothalonil WP to mix evenly in the ratio of 1:1, and dress in the 0.3% weight of seeds, then seal up for 2-3 days before sowing.
 
C, Agricultural control. Avoid planting in low-lying wet land; rotated with non-legume crops; proper close planting to make ventilation and illumination in field; attention to drainage to reduce field humidity; supply adequate base manure, adding potash fertilizer in order to enhance plant resistance to disease; clear away residual body of disease in field
 
D, Chemical control. In the early stages, spray 2000 ~ 3000 times of 25% triadimefon WP, 1000 times of 50% carbendazim WP, or 1000 times of 70% thiophanate-methyl WP, once in every 10-15 days, continue for 2-3 times. It can also by broadcasting a copy of sulfur powder mixed with 3 copies of lime powder on leaf. Or spray 0.3 baume degree of lime-sulfur on leaf; Or spray 500 times of 50% thiophanate-methyl WP added with 200 times of polysulfide, once in 7-10 days, continue for 2-3 times. Good effect can be achieved.
6.1.2. Root rot disease
The disease primarily damages roots or rhizomes. The leaves in bottom layer of the disease plant become yellow first, and it develops upwards to cause yellow and wilting of the whole plant. The main and side root become black, and the vascular bundle become brown or red-brown when cut longitudinally. If the disease is serious, the base root will becomes shringking or hollow and brown, with rotten cortex in disease part, to make dwarf plants. The leaf will be small in light-green color, the pods will be less with small beans, and the yield will be lower. Serious disease will causes a large number of dead after flowering, resulting in a full-brown fields, and even no crops. The disease can occurs throughout the growing period, but more likely to infect in flowering period. The bacteria is soil-borne, spreading via soil, residual body of disease, or seed. The proper attacking temperature is 24-33 degree celsius. Drought years and continuous cropping field will lead to serious disease.
 
Control methods.
Irrigate root by 3000 times of 95% hymexazol No. 1 WP, 600 times of 80% hymexazol No. 2 WP, or 500 times of 20% of Thiodiazole-copper SC. According to reports, for reverse cultivation in Summer and Autumn, the root rot disease occurs seriously. It is proved by experiment that chemical control is the effective ways to control this disease in reverse cultivation. The use of seed dressing and root irrigation by chemicals has good effect. For seed dressing, the chemicals can be chosen including thiram, carbendazim and chlorothalonil. For root irrigation, the effect of hymexazol and carbendazim is the best, but the cost of hymexazol is too high. The effect of dixon and chlorothonil is high, and they can be rotate with carbendazim. Early stage of disease is the proper period for control, and the best control effect is by root irrigation. For to reduce cost of pesticide and pollution to environment, the spraying to base stem can also be used, which will get good effect in short term, but to apply continuely for 2-3 times because the potency peroid is limited. The plastochrone for root irrigation is 10-15 days, and 7-10 days for spraying. At the same time, pay attention to the alternating application of pesticides in order to delay the time to generate resistance. In Summer and Autumn, as the temperature is high, the seed dressing by dixon, and triadimefon will produce phytotoxicity, significantly restaining seed germination, coupled with many showers in Summer and Autumn, the seed can not germination because the harden of surface soil. Therefore, it is not suitable to use dixon and triademefon to dress seeds for reverse cultivation in Summer and Autumn
6.2, Control of Pest
6.2.1, Leafminer
The damage characteristics of leaf miner in pea pods are as follow. The larva sneak into and damage leaf flesh, and bores through leaf for eating leaf flesh. In the leaf surface, winding snake-like tunnels can be seen. The leaf epidermis turns into gray white color after been eaten. It can cause wilt of leaf in whole plant. This pest occurs mainly within the period of flowering and podding, yield and quality will be impact greatly when it occurs serioudly.
 
Control method.
①     Eradication of insect source. As the egg, larvae and pupa states are all spent in leaf, using the redual body as feed or compost after harvest will wipe out abundant of redual pests. The population of the next generation can be reduced by clear away the weed in and around field
 
② Use of natural enemies. Take full advantage of natural enemies to control the leaf miner populations. In the great occurrence season for natural enemies, avoid use of chemical pesticides or choose to use pesticides as far as possible in order to protect natural enemies in field. One of the enemies for larvae is eulophid, and for pupa is Asobara tabida.
 
③ Chemical control. When the larvae become visible, it is the best time for the first chemical control. After that, spray once in 7-10 days. 1000 times of 50% phoxim EC, or 1000 times of 40% (abamectin+dichlorvos) EC can be used. It can also spray attractant in the eclosion acme of wintering imago to achieve good effect. The specific method is as follow. Spot spray 10-20 plant in every 11 sq.m. of field. The preparation of attractant is that, use cook liquid using potato leaves or carrot as bait, add with 0.05% trichlorfon as poison. Spray once in every 3-5 days, totally for 5-6 times. To seize control time in spawning period and hatching period will achieve the best control effect.
6.2.2, Soybean stem borer
This pest occurs seriously along the coast in Fujian province, and spread to mountainous areas. It damage many kinds of leguminous crops, and the generations overlap. The larvae bores into stem for damage, eating into core and xylem. When the larvae is mature, it bit an in the stem wall to bite an eclosion hole on the stem wall and then pupate. The bottom leaves of disease plant turn yellow and the disease develop upwards. In severe cases, the stem becomes hollow and the leaf shedding, the plant will wilts gradually due to disruption of water and nutrients. When the damage occurs in seedling stage, the organic nutrients will accumulates because of the disruption of delivery of nutrients, which will stimulate cell proliferation, resulting in the intumescence of root and stem and cracking sometimes. The dwarf plants is easily attacked by root rot disease because of the week growing potential and many wounds. If the disease occurs in late period, it will easily causes early dropping of flower, pod and leaf, and reducing in yield. Because the overall appearance of disease symptoms of plant in early affected period, it is hard illegible for farmer. This often leads to medication errors, missing the optimum control period, resulting in reducing yield, and even no crops.
 
Control methods. Prevention and control should be the focus on seedling stage. Root-irrigation or spray by 2000 times of 1.8% avermectin EC, or 1000 times of 48% chlorpyrifos EC for control.

6.2.3, Aphid
The damage is by absorbing leaves juice and spreading the virus.

Control methods.
①Agricultural control. Strengthen field management and prevention of drought.
②Use of natural enemies. Natural enemies of aphids include syrphus fly and ladybird
③Use of tropism to yellow color. Make use of the tropism for yellow color, coat engine oil or pesticide powder on a yellow board to attract and kill aphid.
④Chemical control. Spray 2500 times of 50% pirimicarb WP for control.
6.2.4, Liriomyza sativae
It is mainly by larva and female imago which damage the sweet and crisp leaf, also to fruit. The larvae eats the palisade tissue inside leaves, reserving the white epidermis. The insect road widens and lengthens gradually, making the leaf to become mottled, even to wither and fall off. When the imago damages, it punctures the leaf epidermis and lick juice, leaving many white cicatrice on leaf surface, and destroying mesophyll cells and chlorophyll, which will reduce leaf photosynthesis. At the same time, because there is a wound on leaf, the leaf will be invadeded by bacteria easily, resulting in disease incidence and prevalence. When the worm damages fruit, it will leave white spot and insect road on fruit skin. The amount of of worms in back leaf is less.

Control methods
①Prevention mainly and comprehensive management. It is mainly by the prevention and control of protected areas in Winter and Spring, to reduce the insect source in open field, and timely eradication of adult and newly hatched larvae. At the same time, make use of the high temperature in Summer to seal shed or low temperature in Winter to freez shed, to effectively reduce the insect population base.
②Enhancing fertilizer and water management. As far as possible, supply less nitrogen fertilizer and more organic fertilizer. In pupation acme, water and plough deep properly, to create unsuitable circumstance for eclosion.
③Use of natural enemies for biological control. First, make use of parasitic enemies to live mainly at the larval stage. Many kinds of parasitic wasp which mainly belong to eulophidae should be protected greatly. Second, make use of predators, such as Orius minutus, thrip, etc. to eliminate pests
④Use of tropism to yellow color. Use the waste plastic bottles which is painted with yellow paint to kill the adult.
⑤Chemical control. The common used agents include confidor, abamectin, etc, with good control effect. The medication time is from 8-11 am, and after 3 pm, with 5-7 days of plastochrone. Spray mainly on the middle and upper leaves on front side.

7, Harvest

The snow pea belongs to the fruit vegetables which are sold in tender pod, which make it important to master the degree of maturity in picking. If harvest too late, the sugar in pod will reduces and the starch and fiber increases, the crisp and sweet flavor will go bad; if harvest too early, although pods is crisp, the yield will be reduced. Timely harvest when the pod grows to maximum in size and thicken, the bean is going to develop, and the appearance of pod just illustrating shape of beans. In this way, it will not reduce yield and also not impact the growth of young pod. Generally, for soft pods varieties, it is better to harvest earlier, about 10 days after blossom. The harvest of pods is in the morning generally. Pick the pods carefully, and retain 0.5cm of pedicle. Pack pods by bamboo basket or plastic box after grading, and sold to market in time.