Organic production of garden pea in the highlands
GARDEN PEA ( Pisum sativum L.), known as “sweet pea” in Benguet is primarily grown for its fresh pods, edible green seeds, and is also used as dry seed crop. It is an annual leguminous crop and usually self-pollinated. The pods are about 7.62 centimeters (cm) (or 3 inches) long and contain four to nine seeds that may be round, angular, or wrinkled (Ware and Swiader 2002). Garden pea is one of the most important food legumes in the world production and it can be grown practically in all parts of Benguet, with the central and southern towns as major production areas. It is one of the most expensive vegetable legume crops grown by Benguet farmers.
USES AND NUTRITIONAL VALUE
Garden pea is a popular ingredient in ‘chopsuey’ and ‘pancit’. It can also be added in soups, sautés, and any dish with mushrooms, bamboo shoots, and shrimp. This vegetable is marketed fresh, canned, or frozen while ripe dried peas are used whole, split, or made into flour. In some parts of the world, dried peas are consumed split as dahl, roasted, parched or boiled, and used in a growing snack market. Garden pea is rich in protein and vitamins (Table 1). It is considered as the “poor man’s meat” especially in developing countries where meat is expensive (Purseglove 1972).
In the project “Variety Evaluation, On-farm Trials and Seed Production of Organic Vegetables in Cordillera Administrative Region”, crop varieties were selected and evaluated under organic production systems in Benguet. Performance of selected varieties were further evaluated on-farm. Field trials were conducted in La Trinidad and Atok, Benguet across various mountain zones and seasons (Tad-awan et al. 2013). Of the six garden pea varieties evaluated, CGP 34 produced the highest fresh pod yield in evaluation trials across locations. Chinese selection has been recommended in high mountain zones. CGP34 and Chinese Selection were the entries preferred by most farmers. Betag is recommended in mid-mountain zones, although it is least preferred by farmers. The criteria for selection of garden pea entries for organic production are: narrow and medium-sized pods, long shelflife, high yield, and resistance to powdery mildew (Table 2). Figures 1-9 show CGP 34, Chinese selection, and Betag plants, pods, and seeds.
SOIL AND CLIMATE REQUIREMENTS
Garden pea requires well-drained, clay loam soils. It grows well in humus-rich or volcanic soil (Chapman and Carter 1976). It also requires a reasonable level of soil fertility and a pH of 5.56.5. Pea crops cannot tolerate very acidic soils or waterlogging.
Garden pea is a semi-temperate legume grown at about 1,500 meters (m) above sea level and favors a cool climate with a
temperature range of 10OC-18OC. In lower elevations, the plants are less vigorous and are more prone to diseases, including powdery mildew. Moreover, their pods are more fibrous.
Select a well-drained area and with clay loam soil. Clean and prepare the area through weeding or by use of grub hoe or trowel. Construct plots with a dimension of 1 m x 10 m or depending on the farm size. Height of plot should be 15 cm during rainy season and 10 cm during dry season. Pulverize the soil to make it friable and without weeds.
Plant garden pea at the end of the rainy season, starting from October until December. Sow 2-3 seeds per hill at a depth of 2-5 cm. Distance between hills is 30 cm while distance between two rows is 25 cm.
“Organic fertilizer is any product in solid or liquid form, of plant (except byproducts from petroleum industries) or animal origin that has undergone substantial decomposition that can supply available nutrients to plants with a total nitrogen (N), phosphorus (P), and potassium (K) of 5%-7%. This may be enriched by microbial inoculants and naturally-occurring minerals but no chemical or inorganic fertilizer material has been added to the finished product to affect the nutrient content” (DABAFPS013).
Organic fertilizer improves soil tilth and structure; increases soil’s ability to hold water and nutrients; supports living soil organisms; helps dissolve mineral forms of nutrients; buffers soil from chemical imbalances; provides biological control of certain soil pests; and helps return organic materials to the soil.
“Compost/soil conditioner is any product in solid or liquid form, of plant (except byproducts from petroleum industries) or animal origin that has undergone substantial decomposition. It can supply available nutrients to plants with a total NPK of 2.5%-5%. This may be enriched by microbial inoculants and naturallyoccurring minerals but no chemical or inorganic fertilizer material has been added to the finished product to affect the nutrient content” (DA-BAFPS 2013). Compost and soil conditioner are used interchangeably in the Philippine National Standards on Organic Fertilizer.
Biofertilizers contain beneficial microorganisms and humus, which help improve the physical, chemical, and biological properties of the soil, which are essential in crop production.
In producing compost, the following procedure can be followed (PCAARRD 2015). Construct composting shed using locally available materials and in a place far from the crop area and water resources. It should not be located in a land subject to flooding. The minimum equipment needed in producing organic fertilizers include shredder, drums for water storage, flat and pointed shovels, Japanese hoe, wheel barrow, sieve, and water hose.
The raw materials used for organic fertilizer production under BSU conditions are dried chicken manure, sawdust or coco sawdust, wild sunflower, and Trichoderma (Fig. 10). Dried chicken manure is preferred over fresh chicken manure. Fresh chicken manure contains contaminants and harmful microorganisms and emits foul odor. Sawdust or coco sawdust from lumber that are not chemically-treated is recommended. This material is an excellent source of recalcitrant carbon in inorganic fertilizer. Recalcitrant carbon has been found stable in soil, thus it aids in maintaining good soil structure. Wild sunflower is known to be rich in nitrogen. Adding it to the pile increases the nitrogen content of the organic fertilizer. It is found everywhere in the place and available almost all year-round. It is useful because it adds to the organic matter content of the compost. Trichoderma is a fungus found to be an efficient decomposer because it enhances the composting process. It is isolated from the soil, decaying organic wood, and other forms of plant organic material.
STEPS IN PRODUCING COMPOST
1. Collect raw materials. 2. Shred the raw materials to 1-inch or 2-3 cm diameter or smaller to enhance the decomposition, specifically of tough and fibrous plant tissues. Shred the wild sunflowers with stems of up to 2-3 cm to provide a greater surface area for decomposition. To enhance decomposition, pulverize the chicken manure and sawdust, particularly those that turned into lumps. 3. Pile the shredded raw materials layer by layer (Fig. 11). Prepare a maximum of six layers (or 1.5 m thick) of materials. The ratio of raw materials is 50% chicken manure, 25% sawdust or coco sawdust, and 25% wild sunflower. A layer of sawdust or coco sawdust is usually spread first to absorb excess water. Then chicken manure is piled on top of the sawdust. Above the layer of chicken manure is another layer of sawdust or coco sawdust, after which a layer of the shredded wild sunflower is spread. Trichoderma is usually spread as thin layer.
Stack the layers until the pile reaches 1.5 m high. There is no need to put ash/lime or bamboo breathers.
Monitor the temperature of the compost pile with a thermometer (0-200) OC with a long probe. The temperature should be maintained between 40OC and 60OC for 3 weeks.
4. Water each layer of raw materials after piling (Fig. 12). Thereafter, water the pile regularly, at least 2-3 times a week. Moisture content is best between 40% and 60%. Avoid adding too much water into the pile to prevent anaerobic decomposition. Foul odors are from anaerobic activity and indicate lack of oxygen. If the pile becomes too wet, increase turning frequency and/or add fibrous materials to the pile to reduce the moisture content and increase oxygen.
5. Turn the compost pile from top to bottom after two weeks from piling. Repeat this every week thereafter until the pile has fully decomposed. Mix the pile to break down tough and fibrous plant materials efficiently. By doing this, the moisture and organisms that help breakdown the raw materials are distributed evenly in the composting materials.
If fungus compost activator such as Trichoderma is applied, the pile takes 1-2 months to decompose. However, the decomposition process without the fungus activator takes 2-3 months.
PRODUCTION OF ORGANIC PLANT SUPPLEMENT
“Organic plant supplement is any compound of organic origin in liquid or solid form which in low concentration promotes or modifies physiological processes in plants. Total NPK is 0.5%-2.5% and may contain beneficial microorganisms, micronutrients, and plant growth regulators. These plant supplements include, but are not limited to fermented plant juice, fermented fruit juice, fish amino acid, fish emulsion, seaweed extracts, vermi tea, compost tea, and the like” (DA-BAFPS 2013).
The BSU project on “Organic Fertilizers and Microbials for Improved Soil Fertility in Organic Vegetables Production in the Cordillera Administrative Region”, experimented on various organic materials and came up with formulations, which provided nutrients that are important during the plant’s vegetative and reproductive stages. The supplements contain N and other essential macro- and micronutrients in sufficient amounts and assimilable forms (BSU-PCAARRD 2013). The procedure adopted is as follows: 1. Use legume seeds such as soybean and bush bean seeds to produce fermented liquid organic plant food supplement. These seeds provide higher nitrogen content. 2. Soak the seeds in water for about one hour. 3. Boil the seeds for 30 minutes and then let them cool before grinding. 4. Use a blender to grind the boiled seeds. 5. Ferment the material using a ratio of 1:1:1 of ground seeds, molasses, and water. Add one cup dry yeast per kilogram of ground seeds. 6. Ferment the mixture for a month. 7. After fermentation, filter the mixture through a white cotton cloth. 8. Boil the filtrate at 80OC and then allow to simmer. Once cooled, the filtrate is ready to be applied.
PREPARATION OF LIQUID TRICHODERMA KONINGII
T. koningii is a beneficial fungus. It was isolated from Benguet soils in 1997 and later developed as a biofertilizer and biological control agent after series of experiments. Presently, the fungus is being used in Benguet as biofertilizer and as biological control agent against soil-borne plant pathogens. Galian and Nagpala (2006), demonstrated that T. koningii applied as biofertilizer n garden pea at rates of 10 g, 15 g, 20 g, 25 g, and 30 g improved plant height with higher fresh and ovendry weight, higher yield, longer pods, and bigger rot nodules (improved nodulation). The same garden pea plants applied with T. koningii also produced bigger size of root nodules. As biological control agent, garden pea plants applied with T. koningii resulted in low Fusarium wilt infection.
The fungus is prepared or grown in artificial media potato dextrose agar (PDA) in the laboratory for 5-7 days, after which the surface growth is carefully scraped and mixed thoroughly in 16 liters (L) water. After thorough mixing, the liquid preparation of T. koningii can be applied onto the soil using a knapsack sprayer. The beneficial fungus is produced or prepared at the Plant Health Clinic of Benguet State University.
APPLICATION OF TRICHODERMA KONINGII IN FIELD PLOTS
Before applying the compost, the liquid Trichoderma can be directly sprayed in field plots and thoroughly mixed with the soil. This is a practical way of applying the beneficial fungus in the soil. It is also important to moisten the soil with water before or after application for the fungus to germinate. Garden pea seeds can be sown in treated plots, two weeks after T. koningii application.
T. koningii is known to help in the solubilization of nutrients present in the soil. Treating the field plots with Trichoderma will also protect the roots against soil-borne pathogens such as Fusarium oxysporum f. sp. pisi causing root rot and wilt of garden pea in the field.
APPLICATION OF COMPOST AND ORGANIC PLANT SUPPLEMENT Before sowing garden pea seeds, uniformly apply 1.5 kilograms (kg) compost per 5 square meters (m2) area in furrows or in hills. Thoroughly mix the compost with the soil. Apply another 1.5 kg of compost per hill near or around the base of the crop, 10-15 days after seedling emergence and then cover this with soil. Application at this stage is necessary to continuously provide the essential nutrients needed by the crop.
Before hilling up, which is usually done 30 days after transplanting, apply another 2.5 kg/5 m2 of compost as side dressing near or around the plants, then cover it with soil.
Apply liquid organic plant supplement 15 days after transplanting at the rate of 60 mL per liter of water. This can be done every week to provide the crop with additional nutrients. The liquid organic plant supplement is either applied as drench at the base of the crop or as foliage spray.
Figure 14 shows the different organic products that BSU developed, tested, and used in growing organic garden pea.
Irrigate the crop using a sprinkler or by manual watering, 2-3 times a week until harvesting period. Monitor soil moisture levels closely and irrigate when necessary.
Remove weeds early to prevent competition with the crop. Pull the weeds by hand or by using a hoe and cultivate the soil in between the rows. Continue to remove the weeds until the plants reach its harvesting stage. Weeding will help minimize insect pest population such as leaf miner.
Practice hilling up 25-30 days after sowing. Apply organic compost in between rows then cover the base of the plants with soil. The applied compost will supplement the nutrient needs of the plants during flowering and pod setting.
Provide trellis 20 days after the seeds have emerged. Blind the plants with plastic twine to allow the plant to cling to the trellis. This prevents the plant from lodging. Continue to train the plants with twine until they reach maximum height.
INSECT PEST AND DISEASE MANAGEMENT
Application of good cultural management is one way of preventing severity of insect pest and disease occurrence in the farm. Such cultural management include planting in healthy soil, using resistant varieties, crop rotation, good soil tillage, time of planting, and weed management. Presented below are the insect pests and diseases of garden pea and their management.
MANAGEMENT OPTIONS FOR MAJOR INSECT PESTS OF GARDEN PEAS
Pod Borer ( Maruca vitrata ( testulalis) Geyer)
Description Full-grown larva is 30-40 mm long, cream to greenish-yellow or bright green, with rows of dark brown spots along the back. The head is dark brown to black.
Damage The larva is the destructive stage. It destroys buds, flowers, and pods. Damaged pods show small entry holes on the surface.
Management Options ● Trap adults by putting light sources at night in the area.
● Apply bioinsecticides such as garlic + yellow ginger + chilli extract. Use vinegar as extractant. These bioinsecticides can be applied singly or in combination. To prepare the bioinsecticides, slice the garlic cloves, ginger rhizomes, and chilli pepper fruits and mix with vinegar which serves as extractant in a 1:1 ratio. The solution should be transferred to clean container with cover. Allow the solution to ferment in 14 days. The liquid will then be filtered using a cheesecloth and stored in a sterile bottle with cover. The fermented extract can be sprayed at a ratio of 1:16 dilution. Spraying is done at 7-14 days interval and starts at the flowering stage of peas. Spraying should be done in the early morning or late afternoon to avoid possible degradation or burning due to high temperature.
● Apply nucleopolyhedrosis virus (NPV) in liquid formulation late in the afternoon or early morning at one NPV-infected cutworm per liter of water. Preparation of NPV can be done by collecting NPV-infected cutworm (worms that are limp or drooping whitish and hanging upside down in the plant) and mixing them with a little distilled water. For every infected cutworm, 1 liter of water is needed. The infected larvae must be grinded or macerated to release the virus particles using a blender or a mortar and pestle. The solution must be filtered using a cheesecloth and an equal amount of 10% ethanol is added to control the growth of bacteria that causes the foul odor of the suspension. The prepared NPV suspension is sprayed onto the plant at an interval of seven days. Spraying begins during the flowering stage.
● Handpick the larvae and pupae during the early stages of infestation.
Aphids ( Myzus persicae, Aphis craccivora, Lipaphis erysime, and Acyrtosiphon pisum Harris)
Description The body is pearshaped, with long, tiny legs and antennae. They have needle-like mouthparts that are used for piercing and sucking plant juice. Aphids are greenish, brownish, or blackish, depending on the species and kind of food they eat. They reproduce when there is much food and even without males. If there are no males, the mother lays nymphs but if there are males, then the mother lays eggs.
Damage The nymphs and adults are both destructive to plants. They stay on the shoots or young leaves, make small holes, and sip the plant juice. The honeydew they produce attracts fungus (sooty mold) that rapidly covers the leaves.
Management Options ● Use yellow pan traps with water.
● Apply bioinsectides such as garlic + yellow ginger + chili using vinegar as extractant singly or in combination. To prepare the bioinsecticides, slice garlic cloves, ginger rhizomes, and chili pepper fruits and mix with vinegar which serves as extractant with cover. Allow the solution to ferment in 14 days. Filter the liquid using a cheesecloth and store in a sterile bottle with cover. The fermented extract can be sprayed at a ratio of 1:16 dilution. Spraying is done at 7-14 days interval starting at one month after planting. Spraying should be done in the early morning or late afternoon to avoid possible degradation or burning due to high temperature.
● Use NPV in both liquid and powder formulations at one infected cutworm per liter of water. Spraying should be done early in the morning or late in the afternoon.
● Spray Mokosaku or wood vinegar (2 tbsp/16 L of water). Mokosaku can be obtained from the Municipal Agricultural offices in each municipality of Benguet and some organic farmers.
● Remove the affected plant parts and burn.
● Use high pressure sprinkle irrigation to knock the insects off the plants.
● Plant insect repellant crops such as marigold, zinnia, cosmos, onions, corn, and bush beans along borders to maintain population of natural predators.
Leaf Miner ( Liriomyza huidobrensis Blanchard)
Description The adults are brownish two-winged flies with yellow stripes in the body, 2-2.5 mm long. The larvae are elongated, cream, and become cream yellow when about to pupate. Damage The larvae tunnels made by the larvae between the lower and upper leaf epidermis interfere with photosynthesis and growth of the plants and make them look unattractive.
Management Options ● Place sticky, yellow traps in between plots.
● Apply bioinsectides: extract of garlic + yellow ginger + chili using vinegar as extractant. These bioinsecticides can be applied singly or in combination. To prepare the bioinsecticide, slice garlic cloves, ginger rhizomes and chilli pepper fruits and mix with vinegar which serves as extractant in a 1:1 ratio. Transfer the solution to a clean container with cover. Allow the solution to ferment in 14 days. Filter the liquid using a cheesecloth and store in a sterile bottle with cover. The fermented extract can be sprayed at a ratio of 1:16 dilution. Spraying is done at 7-14 days interval starting at three weeks after planting. Spraying should be done in the early morning or late afternoon to avoid possible degradation or burning due to high temperature.
● Apply NPV both in liquid and powder formulations (one NPV-infected cutworm per liter of water). Spraying should be done early in the morning or late in the afternoon.
MANAGEMENT OPTIONS FOR MAJOR DISEASES OF GARDEN PEAS
Fusarium Wilt ( Fusarium oxysporum Schlecht)
Description Fusarium wilt is an important soil-borne disease of garden pea. Maximum profitability in the crop is not attained if infected with Fusarium wilt disease. It affects the vascular tissues of the plant; interferes with water conduction and produces toxins, which cause wilting. Infected plants wilt and eventually die without reaching the productive stage. According to Smykal et. Al. (2012) about 60% yield loss is incurred due to Fusarium wilt.
Symptoms Curling of leaves is one of the first symptoms noticeable in plants affected with Fusarium wilt, followed by leaves and stems turning light green. Since the fungus affects the vascular tissues, wilting is observed especially when temperatures are high. As the disease develops, discoloration of root tissues is observed. A cross section of the stem right above the root system would reveal a pinkish to red vascular tissues. Yellowing starts from the lower leaves to the plant tip, which progress to the stems
that become somewhat rigid then followed by death of the plant. Disease development depends on the prevailing weather conditions. If plants are affected at an early stage of plant growth, it is likely that the plant would die even before reaching the productive stage. When affected during a later stage, the plant may survive but yield performance is poor.
Management Options ● The use of resistant varieties such as Betag, CGP 110 and CGP 154 is the best way to manage Fusarium wilt. CGP 59, 11, and 34 have intermediate resistance to Fusarium wilt.
● To ensure protection of the plant and to prevent multiplication, drench the soil with garlic extract prepared using strawberry vinegar as extractant before planting.
Powdery Mildew ( Erysiphe pisi)
Description Powdery mildew is a serious disease causing severe losses in garden pea production. It occurs frequently and covers a large area of the plant surface. Once plant is infected, its processes are hampered, thereby affecting plant growth and development. A 70% yield loss in individual crops has been attributed to the disease.
Symptoms Infected plants exhibit white powdery growth on leaf, stem, and pod surface. This powdery growth is easily rubbed off. It usually occurs as white spots on the surface of older leaves, which then rapidly cover the entire leaf surface and spread upwards towards the stem, younger leaves, and pods. Leaves eventually wither and dry up.
Management Options ● Cultural Control - Use resistant varieties such as Betag and CGP 34. - Plant early. - Maintain farm hygiene.
● Biological Control - Use EYCOG, a mixture of egg yolk + canola oil + garlic extract. This is prepared by mixing 1 egg yolk, juice from 30 g garlic cloves extracted using a juicer, and 10 mL canola oil. Spray garden pea plants with 72 mL/16 L water before the onset of the disease and repeat at 7-day interval. Shorten spraying interval if the disease pressure is high. - Use Bacillus subtilis. Spray 1 bottle (50 mL)/L water at 7-day interval. Shorten the spraying interval if the disease pressure is high. Spaying should be done preferably in the morning or late in the afternoon. - Process of mass producing B. subtilis: 1. Grow B. subtilis in test tubes containing nutrient agar and incubate for 48 hours. 2. Prepare the bacterial suspension and inoculate into the sterile chayote broth at 0.1 mL/bottle. Prepare chayote broth through the following steps: a. Boil 300 g peeled and chopped chayote in one-liter distilled water. b. Add 50 g table sugar then filter. c. Dispense 50 mL of the solution in mayonnaise bottles and autoclave at 15 psi for 15-30 minutes. 3. Incubate the inoculated bottles at room temperature for another 48 hours while occasionally mixing the broth and bacterial growth using a mechanical shaker (i.e., 30 minutes in the morning and 30 minutes in the afternoon). 4. Blend the mixture to homogenize and then strain.
This procedure is usually done at the laboratories of academic and research institutions due to unavailability of equipment in other places. The bacterial suspensions are available by order at the Horticulture Laboratory of BSU. HARVESTING Harvest the pods at 55-60 days after sowing or when the pods are fully green and well developed but still tender. The seeds should be near full size and should not have begun to harden. Handpick the pods before the seeds are fully matured. Some growers do only one picking while other growers have two or five pickings, depending on pod maturity. Frequent harvesting is necessary. Keep the produce under shade and pack in plastic crates. Pods can be stored for 1-2 weeks at 0OC (32OF) and 95%-98% relative humidity.
COST AND RETURN
Table 3 shows that production of different varieties of garden pea during the dry season of 2012-2013 resulted in net incomes ranging from R20,000 to R60,000. Returns on cash expense (ROCE) ranged from 47% to 134%. (PCAARRD INFORMATION BULLETIN)
Table 2. Recommended garden pea varieties for organic production.
Fig. 4. Plants of Chinese selection.
Fig. 7. Plants of Betag.
Fig. 1. Plants of CGP 34.
Fig. 6. Seeds of Chinese selection.
Fig. 9. Seeds of Betag.
Fig. 3. Seeds of CGP 34.
Fig. 5. Pods of Chinese selection.
Fig. 8. Pods of Betag.
Fig. 2. Pods of CGP 34.
Fig. 10. Raw materials (sunflower and sawdust) in the production of organic fertilizer/ compost.
Fig. 11. Piling of raw materials.
Fig. 13. Five-day old pure culture of Trichoderma koningii.
Fig. 12. Watering of compost pile.
Fig. 14. BSU liquid organic plant supplement (a), TRI-BIO ( Trichoderma koningii) microbial inoculant (b), and growers’ compost with and without bio-char (c and d).
*Total cost of production includes the cost of planting materials, trellis material, organic pesticides (Mokusako), and organic fertilizer. Selling price of fresh pods is based on R200/ kg. Table 3. Cost and return of organic production of garden pea in different locations, 2011-2012 dry season cropping.