Project Leader: Alton S. Arakaki, County Extension Agent Location: Moloka i Applied Research Farm, Hoolehua, Moloka i, Hawai i

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1 CASE STUDY: Growing Vegetables in Living Shield Cover Crop Project Leader: Alton S. Arakaki, County Extension Agent Location: Moloka i Applied Research Farm, Hoolehua, Moloka i, Hawai i Situation There is great interest in sustainable farming on Moloka i. Sustainable farming and farming methods promotes production practices that incorporate existing geographical and biological environments. Farming methods such as cover crops, trap crops, in-field insectaries, multicropping, green manuring and fallow management are applied to enhance crop production in these environments. Farmers that practice sustainable farming advocate less use of farm chemicals to manage crop pest. Farming sustainably and using less or no pesticides promotes environmental quality and have become a marketing concept and tool. Farmers practicing organic farming or not applying farm pesticides have found a marketing niche for their products. Products that are labeled organic and pesticide free have gained shelf space in the produce section of the market. Thus growing crops using sustainable methods has provided family farms with marketing opportunities. However with the all year round growing season in Hawaii, managing insect pest has become one of the most difficult tasks in vegetable crop production. Under this favorable condition, populations of insect tend to survive in the environment throughout the year. If there are no crop hosts, insects have adapted to survive on alternative weed host. There is a need to develop alternative insect management practices in sustainable farming that reduces the requirements to use chemical insecticides. In weed management living mulch studies conducted by J. DeFrank and in demonstrations by A. Arakaki, it has been documented and observed that less insect damage occurred on vegetables planted in treatments with companion grass living mulch. In living mulch practice, companion grass mulch is grown in the field in which broadleaf vegetable crops planted. Living mulch is management by chemical stunting or mowing. In this growing arrangement ground and weeds are shaded, thus reducing weed population. Insect crop damage also was reduced in this growing arrangement. However in these studies and demonstrations, crops grown in living mulch resulted in lesser yields and later maturity than crops grown conventionally. The reduction in yield and later maturity were attributed to shading, cooler ground temperature and competition for plant nutrition. Some crop quality loss was attributed to the scars and scrapes on the vegetable, especially on fruity vegetables, caused by rubbing of living mulch. Project Goal The goal of this project is demonstrate the effectiveness of nonchemical living shield method to manage insect damage in vegetable production. Like living mulch method, living shield utilize grass companion plant in broadleaf vegetable crops. But rather than selecting and planting companion grass that will cover the ground completely, living shield will utilize companion grass that can be grown and managed between crop beds or rows. This between row Overview of Sustainable Techniques Used Sterile Seed Bed Living Mulch for weed and insect control Demonstration Field Layout Field Plots with Living Shield Treatment #1 Field Plots Without Living Shield Treatment #2 companion grass planting method will increase ground temperature, increase sun exposure on crops and reduce plant nutrient competition. 1. Select companion grass for living shield: For this demonstration project Buffelgrass, Cenchrus ciliaris, Pennisetum ciliaris, was used as the companion living shield. Buffelgrass is highly drought resistant, not a favorite host to root knot nematodes, bunch-type perennial grass. 2. Prepare field: Disced, marked and installed crop beds, applied preplant fertilizer and installed drip irrigation system. Marked living shield plots and non-living shield plots. 3. Conducted sterile bed procedures to reduce first generation weed population: a) irrigated field and germinated weed seeds (2 weeks) b) destroyed germinated

2 First generation of weeds germinated after two weeks of irrigation. weeds (flaming, contact herbicides), with minimum disruption to soil surface. For the demonstration contact herbicide was applied. 4. Planted shield buffelgrass between crop beds. 5. Planted vegetable crops on beds in plots treated with buffelgrass living shield and those without living shield. Vegetable crops included tomato, bush green beans, head cabbage, eggplant, romaine lettuce, and zucchini. 6. No insecticides applied on both treatments, with and without living shield. 7. No cutting back of buffelgrass living shield. Destroy germinated weeds. Repeat Buffelgrass living shield rows prior to planting vegetable crop. Open bed increases sun exposure on crop area. Seeding buffelgrass between crop beds. grass living shield vegetable bed grass living shield vegetable bed grass living shield Results 1. Insect damage rating, from 0 to 100, 0 being no damaged and 100 being extensively damaged. Conducted rating at 30 days after planting or transplanting, (DAP) mid-plant maturity, Evaluators Guide to Visual Damage Rating a. 0 to 30 = insect damage does not warrant management intervention b. 31 to 60 = insect damage warrant application of management intervention c. 61 to 100 = intervention required, insect damage at level that will result in economic losses

3 Table 1. Insect Damage Rating 30 DAP Mid-Maturity Maturity Insect Rating Insect Rating Insect Rating Tomato With Living Shield 0 Whitefly 18 Fruit fly 38 Leafminer 5 Fruitworm 65 Whitefly 10 Leafminer 8 Without Living Shield 0 Whitefly 25 Fruit fly 48 Leafminer 12 Fruitworm 78 Whitefly 25 Leafminer 8 Romaine Lettuce With Living Shield Webworm 7 Whitefly 7 Whitefly 5 Aphids 10 Without Living Shield Webworm 7 Whitefly 15 Whitefly 5 Aphids 12 Bush Green Beans With Living Shield Rose Beetle 2 Rose Beetle 20 Mites 0 Mites 28 Without Living Shield Rose Beetle 9 Rose Beetle 95 Mites 2 Mites 85 Head Cabbage With Living Shield Webworm 8 Caterpillar larvae 30 Caterpillar larvae 45 Whitefly 10 Without Living Shield Webworm 20 Caterpillar larvae 45 Caterpillar larvae 52 Whitefly 20 Zucchini With Living Shield Aphids 5 Terminate planting Whitefly 10 Silverleaf Leafminer 6 Virus Symptoms Fruit flies in stems 10 Without Living Shield Aphids 9 Terminate planting Whitefly 12 Silverleaf Leafminer 2 Virus Symptoms Broccoli With Living Shield Webworm 8 Caterpillar larvae 32 Caterpillar larvae 40 Whitefly 7 Without Living Shield Webworm 15 Caterpillar larvae 15 Caterpillar larvae 36 Whitefly 10 Cucumbers With Living Shield Whitefly 5 Whitefly 8 Whitefly 15 Fruit flies in stem 5 Fruit fly 75 Aphids 12 Aphids 15 Without Living Shield Fruit flies in stem 10 Fruit flies in stem 20 Whitefly 20 Whitefly 5 Whitefly 15 Fruit fly 100 Aphids 20 Aphids 15 Eggplants With Living Shield Whitefly 7 Whitefly 15 Whitefly 15 Rose Beetle 8 Rose Beetle 20 Rose Beetle 15 Mites 30 Mites 32 Without Living Shield Whitefly 10 Whitefly 20 Whitefly 15 Rose Beetle 15 Rose Beetle 32 Rose Beetle 48 Mites 32 Mites 68

4 Table 2. Yield Data Tomato Romaine Green Beans Head Cabbage Broccoli Cucumber Eggplant (lbs/plt) Lettuce (lbs/25 ft row) (lbs/head) (lbs/head) /25 feet row (lbs/plant/wk (lbs/plt) for 6 wks hrvst) Buffelgrass Buffelgrass Buffelgrass Buffelgrass Buffelgrass Buffelgrass Buffelgrass Treatments w w/o w w/ow w w/ow w w/ow w w/ow w w/o w w/ow Avg. yield % Yld. Diff. 44% 28% 38% 29% 57% 53% 35% Note: No yield data for zucchini. Plants destroyed due to virus infection. Discussions Insects No insecticides were applied in this demonstration project. Evaluators Guide to Visual Damage Rating a. 0 to 30 = insect damage does not warrant management intervention b. 31 to 60 = insect damage warrant application of management intervention c. 61 to 100 = intervention required, insect damage at level that will result in economic losses During the demonstration period there were a group of insects that maintained damage levels below intervention. These insects included whiteflies, leafminers and aphids. Pathogen and virus vectors whiteflies and aphids can cause serious crop loss at low population. This was the case with the zucchini crop. The zucchini crop was infected with virus within 30 days of transplanting by the small whiteflies. Both virus and silverleaf symptoms were present on the plant. Left: Green beans planted between buffelgrass shield. Right: Green beans planted without shield. Insect population was relatively low in both treatments, with and without buffelgrass, at 30 days after planting. In all crops, damage rating did not require insect management intervention. Damage rating ranged from 0 to 20. At mid-maturity insect damage assessment, there was increase in insect crop damage. The insect damage ranged from 5 to 45. See Table 3. Table 3. At Mid-Maturity Rating Crops Requiring Insect Management Intervention >30 Crop With Buffelgrass Without Shield Shield Head Cabbage Caterpillar 45 Broccoli Caterpillar 32 Eggplant Rose Beetle 32 Miles 32 Extensive fruit fly damage to cucumber fruits in both with and witout cover fo buffelgrass shield.

5 Table 4. At Maturity Rating Crops Requiring Insect Management Intervention 31-60; and Economic Losses Occurring Crop With Buffelgrass Shield Without Shield Tomato Fruit fly 38 Fruit fly 48 Fruitworm 65 Fruitworm 78 Green Beans Rose Beetle 95 Mites 85 Head Cabbage Caterpillar 45 Caterpillar 52 Broccoli Caterpillar 40 Caterpillar 36 Cucumber Fruit fly 75 Fruit fly 100 Eggplant Mites 32 Mites 68 Rose Beetle 15 Rose Beetle 48 Crops that reached critical level of insect damage at mid-maturity included head cabbage, webworm in living shield and eggplant, mites in planting without shield. At crop maturity insect damage assessment, insect damage continued to increase. Insect damage reached intervention and economic loss levels. See Table 4. Crop damage from Lepidoptera (moths) type pests (caterpillar, webworm) and fruit flies was consistent in both with and without shield treatments. The consistent caterpillar type damage in the crop is attributed to a consistent population of Lepidoptera pests that was observed in the buffelgrass. Although there was no caterpillar feeding damage on the buffelgrass, to indicate buffelgrass to be a feed host for caterpillars, it is believed that the it provides protection and sanctuary for adult Lepidoptera pests. Therefore buffelgrass may not be a good companion plants for crops that host Lepidoptera pest, such as cabbage, broccoli, and other Crucifer crops. Similar to Lepidoptera pests is the fruit fly. Fruit flies require succulent plant stems and fruits to lay their eggs and complete their life cycle and places outside the field for roosting and protection. There was consistent and similar fruit fly damage in both treatments on tomatoes, zucchini (early) and cucumbers. Although no fruit flies were observed on the buffelgrass, they may be serving as an in-field roosting host for fruit flies. Yields In this demonstration the buffelgrass shield was not cut or trimmed. Shading from the buffelgrass played a major role in the lesser yields in the treated plots. Crops planted without shield yielded 28% to 57% more than crops grown with buffelgrass shield. Even though the crops grown without shield yielded more, in green beans the quality of the harvest was better with buffelgrass shield. With higher population of mites on bean plants without shield, the damage to Growing conditions resulting from the shade of the bufflegrass shield decreases the growth of crops. Tomato and romaine lettuce crops between bufflegrass show less vigor. the harvest was far greater then harvest from crop planted between shields. This project demonstrated that insect damage could be reduced with living crop shield. In most crops grown in the project there was less insect damage in crops between shields than without shields. However in most crops economic losses would occur without managed intervention. Prior to installing companion shield system, careful analysis is needed on the type of pest that will host on the shield crop. You can reduce the pest damage if the crop and the shield crop don t share similar pest or increase damage if they share pests. It is projected that yield can be improved if the height of the shield crop is managed. Buffelgrass grows rapidly and can produce quantities of biomass. Cutting the buffelgrass will increase the sunlight and provide mulch on the crop beds to preserve moisture and manage weed growth.

6 No shield. Higher yield and count but curling and bronzing of beans caused by mite damage. Less yield but higher quality of beans from plants between buffelgrass shield.. Participants Alton S. Arakaki, County Extension Agent Joe DeFrank, Extension Specialist Author: Alton S. Arakaki 10/21/03 This material is based on work supported by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, and the Agricultural Experiment Station, Utah State University, under Cooperative Agreement 00-ESAG