The demand for tomatoes in Palau is quite high. Farmers are keen to grow tomatoes but are hesitant due to many failed attempts, e.g. hydroponics (due to contamination), high tunnels (due to excessive heat, humidity and wind), open fields (due to diseases), high risk, high cost, the prevalence of blossom end rot (due mainly to calcium deficiency), diseases (due partially to overhead watering), cracked fruit (due to frequent heavy rains), losses due to sun scald (20%), fruit flies (70-90%) and poor fruit set (due to hard hitting rain and high night time temperatures).
This project attempted in a systematic, sustainable low-cost manner through shade netting and other methods to overcome these constraints. The project overcame all these constraints except diseases. White flies and aphids were able to find a way into the shadehouses and were vectors for diseases. Due to the rapid build-up of algae and fungus in the shadehouses it is theorized that 50% shade netting does not let in enough sun to keep algae and fungus at bay. Due to the high prevalence of diseases in surrounding areas, solarization only briefly eliminates diseases, for reintroduction of diseases was rapid through air and water.
Tomato production by other producers increased in Palau after first harvest of the project (based on produce records of a leading retailer). The tomatoes grown were marketed through existing marketing channels and complemented the existing produce line by attracting additional and new customers. There is high demand for vine ripened locally grown tomatoes.
The project will increase overall farm production levels by about 12% (based on production levels of first harvest extrapolated) if current constraints are overcome. A leading retailer purchases tomatoes at $1.50/lb. The demand at this retailer exceeds 60 pounds per week. Tangy taste is sought out by consumers. Normally tomatoes are harvested three times a week.
* Maintain and enhance the quality and productivity of the soil through use of a shredder to produce organic materials for mulching, composting and incorporation into the soil.
*Promote crop and enterprise diversification by overcoming the constraints of tropical tomato production through shade netting and other methods in a systematic, sustainable low-cost manner
Briefly, the following activities were completed:
*The site was surveyed, staked, mapped and laid out.
*Solarization of site to kill fruit fly larvae and other pests was completed.
*Shredder was used to produce materials for mulching, composting, etc.
*Plots were soil-tilled, amended and otherwise prepared for planting.
*Shade netting, cages, mulch and EarthBoxes were put in place.
*Seeds were direct seeded.
*For comparison, some seeds were started in pots and transplanted out.
*Project was documented through photo journal and other means.
*Project participants participated in the sub-regional Western SARE Conference in Kona. The farmers’ knowledge-base was expanded by a) participating in the PDP meeting, the ACF (American Culinary Federation) Farmer-Chef Conference and the 18th Annual Hawaii International Tropical Fruit Growers Conference; b) observing what works in Hawaii, c) sourcing technical advisors/specialists; d) witnessing innovative marketing to visitors, and e) learning from tours of successful Western SARE Projects e.g. The Twelve Trees Project, farms and value-adding facilities.
*Pamphlet on growing tomatoes under shade netting was produced.
*For comparison purposes, tomatoes were planted out in an open field using conventional methods and input.
*Turbo-Tomato Mulch shadehouse and container shadehouse were replanted.
*Radio call-in program was produced and aired.
*On-site tours by farmers, agricultural instructors, and students were conducted.
*One article in the leading newspaper was produced and printed.
*Pamphlet on growing tomatoes under shade netting was produced and distributed.
*Screening shown to ‘screen out’ most pests. No instances of fruit flies attacking tomatoes under shade netting. White flies and aphids were able to find a way into the shadehouses.
*Shade netting also prevented losses due to sun scald.
*The shade netting through the mesh released excessive heat, humidity and wind.
*Due to the rapid build-up of algae and fungi in the shadehouses, it is theorized that 50% shade netting does not let in enough sun to keep algae and fungi at bay. We replaced the 50% shade netting on the roof with netting ranging from 25% to 35%. This greatly reduced algae and fungi. This also reduced bacterial diseases.
*The use of tomato cages with a compost pile in the center was not implemented due to the high prevalence on nearby farms of a plant killing fungus associated with partially decomposed organic materials.
*Mulching and amending the soil with burnt egg shells, lime, gravel and coral sand reduced blossom end rot.
*The tomatoes grown were marketed through existing marketing channels and complemented the existing produce line by attracting additional and new customers. There is high demand for vine ripened locally grown tomatoes.
*Enz-Rot Blossom End Rot Concentrate work well in eliminating end rot. Blossom end rot was also reduced when we added lime, crab shells, seas weed and fish emulsion.
*Tomato Set Spray work well improving fruit setting. Fruit setting was improved with the addition of seaweed, crab shells and fish emulsion.
*Bull’s-Eye Bioinsecticide did not at first reduce the white-flies and aphids and Neem-Away did not prevent/reduce fungal infections. Both products seem to be photosensitive and heat sensitive. When we sprayed Bull’s-Eye Bioinsecticide just before dusk we obtain a reduction in white-flies and aphids.
*Tomatoes planted out in open field using conventional methods and inputs experienced the same problems as those under shade netting plus they experienced sunscald, cracking, cat face and later fruit flies. Sevin, Malathion and Chlorothalonil reduced the number and frequency of infestation of white flies and aphids resulting in fewer diseases, more production, and thus a slight economic profit. This slight economic profit is offset by the loss of bees and other pollinators and predators of pests.
*Disadvantages of a shadehouse are: costly in terms of labor, materials and maintenance; ideal climate for aphids, whiteflies and mealybugs, plus reinfection and contamination are possible and may occur easily.
*Site of the project was moved from Airai to Ngatpang with my family’s move to Ngatpang.
*Utilized “used” scaffolding instead of rebars for the structure of shade houses.
*Due to the high prevalence of diseases in surrounding areas, solarization only briefly eliminates these diseases, for reintroduction of diseases was rapid through air and water.
*The control plot planted directly to solarized area bore a good crop and died prematurely due to ‘drowning’, ‘cooking’ and an unidentified white fungus. Some plants ‘drown’ due to poor drainage of the soil and plentiful rain, dew, fog and other precipitation. Some plants ‘cooked’ as the water logged in the soil reached unbearable temperatures due to the burning sun. We are tried to alleviate this problem through incorporation of more organic matter, sand and gravel, variety selection and drainage ditches. These steps were partially successful. An economic return was not realized for the crop. Also high winds on hot days resulted in top layer of soil drying out while bottom layers remained moist. The result being a scarred weak patch of stem at ground level interfering with the intake of nutrients and occasionally breakage of the stem at ground level. Hilling up helped to overcome this. Hilling up one inch of soil around the plant three-five weeks after germination has the benefits of: small weeds close to the plant are smothered; the plants develop roots farther up the stem, better anchoring them; and surplus moisture does not collect under tomato plants where it encourages disease, but instead runs away from the plants.
*50% loss of plants planted under Turbo Tomato Mulch in solarized soil in shadehouse due to ‘drowning’. Similarly, we tried to alleviate this problem through incorporation of more organic matter, sand and gravel, variety selection and drainage ditches. These steps were partially successful. An economic return was not realized for the crop. Doubling the drainage area reduced algae and fungi and did not result in greater production.
*Turbo Tomato Mulch did not increase production of tomatoes under shade netting. Surprisingly, weeds grew under the Turbo Tomato Mulch. These weeds lessened tomato production and increased labor costs and stole nutrients. We have been advised that our black shadecloth filtered out the red rays of sun responsible for boosting the production of tomatoes.
*The first and second batch of tomatoes planted in four- and five- gallon containers in shadehouse all died due to bacterial diseases and white fungus. We theorized the diseases were introduced through the compost used, white flies, aphids and by thieves. Sterilizing the whole shadehouse, sterilization of all materials used, a change of varieties, the addition of coarse gravel at the bottom of the containers and wider spacing resulted in all tomatoes surviving and producing. Also adding seaweed to the potting soil improved disease resistance and resulted in greater production and longer life of the tomatoes.
*While fruit flies have not entered the shadehouses, tiny white flies and aphids have. We tried to lessen them by use of yellow sticky traps (did not work), a soap/oil emulsion spray (worked) and onion spray (partially worked).
*The EarthBoxes work fine. No water logging. No ‘cooking’. 100% survival.
*Plants known to have experienced theft died from a viral disease: tobacco mosaic virus?. Amputating the branch affected effectively eliminated the disease.
Educational & Outreach Activities
Outreach begun at the end of November. Outreach was based on our findings that current constraints severely hamper the profitability of tomatoes as a crop.
Meetings were held with The Bureau of Agriculture, Palau Community College – Cooperative Research and Extension, Palau, Taiwan Farmers Association and Taiwan Technical Mission. A plan was developed and implemented for joint outreach activities. The following activities were jointly done with the above cooperators:
*Production and airing of radio call-in program hosted by Palau Conservation Society.
*On-site tours by farmers.
*One article in the leading newspaper.
*Production of pamphlet on growing tomatoes under shade netting.
We welcome input and advice concerning the project.
The project will increase overall farm production levels by about 12% (based on production levels of first harvest extrapolated) if current constraints are overcome. A significant drop in production occurs after first harvest due to disease pressure. Tomatoes are fetching a high relative price with high demand.
The project: maintained and enhanced the quality and productivity of the soil through use of a shredder that produced organic materials for mulching, composting and incorporation into the soil; maintained the quality of surface water by mulching and the quality of groundwater by using organic fertilizers, thus avoiding artificial chemicals that pollute water; protected the health of the farm family and farm-hands by using organic fertilizers and by using screening to ‘screen out’ pests, thus requiring no inputs of toxic materials and optimizing on-farm resources by turning into mulch by shredding resources such as cassava stems, which otherwise would provide a haven for rats and not be utilized.
Taiwan Technical Mission has requested from the Asian Vegetable Research Center cultivars/landraces of tomatoes suitable to Palau conditions for testing in Palau. Several farmers have expressed interest in growing tomatoes in shelters and buying tomato plants in containers.
Tomato production by other producers increased in Palau after first harvest of the project (based on produce records of a leading retailer). We theorize this is due to a few other producers adopting some of the methods used, plus these producers’ belief if we can do it, they can. We recommend, based on our findings, other producers consider obtaining a copy of “Eggplant, Pepper & Tomato Production Guide for Guam” no.SW99-047, and building a” Greenhouse Water Barrier” no. FW04-302 or a similar shelter.
Comments received from farmers and professionals are:
*“The shade house is good for the environment and relatively cheap and easy to put up.”
*“The shade netting filters too much sunlight.”
*“We have not found any differences between the mulches.”
*“Success is dependent more on variety than method. Test as many varieties as possible.”
*“Forget tomatoes, it is a foreign crop and will not yield a long term profit.”
*“The shade house is good for cauliflower, broccoli, cabbage, …”
*“Switch to growing and selling native ornamentals and traditional healing plants.”
*“Grow a crop that people do not steal.”
*“EarthBoxes makes growing tomatoes easier. We can not afford because the transportation costs nearly doubles their cost.”
*“Using recycled pipes, containers and other materials are thrifty and eco-friendly.”
*“Tomatoes always die at first bloom for me. Come teach me how to do this!”
*“Maybe you can sell us tomatoes seedlings in four-gallon buckets.”
“King Kong”: small, prolific, promising, susceptible to white fungus, ‘drowning’ and ‘cooking’.
“Brandywine”: medium, few fruits, good foliage, gets brown streaks which it survives. Rats have a particular fondness for the fruits, so planting in the open is difficult.
“Farmers 301”: large, vigorous, and susceptible to ‘drowning’.
“Novatos”: medium plum shape, good germination, good fruits, promising.
“Northern Red”: medium, poor germination, good fruits, promising.
“Taichung-Yasu No. 4”: small-medium, susceptible to ‘drowning’.
“Sugar Pearl”: small, weak, susceptible to ‘drowning’ and ‘cooking’, first to die.
“Bangladesh ???”: medium, strong, promising.
“Red Cloud”: small, susceptible to ‘drowning’, does well with good drainage, e.g. EarthBoxes.
“UoH Hybrids”: medium, susceptible to bacterial wilt, and ‘drowning’.
“New No. 4”: believed same or similar to “Asian No. 4”, small, poor germination, slow growing.
“HGP V-180”: large, strong, fine taste, promising.
“HGP V-190”: smaller than cherry, strong, vigorous, promising.
“HGP V-191”: oval, strong, promising.
“King Kong”: small to medium, does well in “virgin” locations, susceptible to disease.
“Rojita”: small, pointed oval, very strong, fine taste, promising, very expensive seed.
“Sugary”: small, pointed oval, very strong, sweetest of all grown and/or tasted, promising, customers preferred.
*Reduce shade netting to 25-35%.
*For control of white flies and aphids, weekly sprayings of seaweed and fish emulsion worked fine. If in the future both pests develop a tolerance to seaweed and fish emulsion and neither provides effective control, try derris and Barringtonia asiatica. Both are locally available insecticidal plants.
*We hypothesize, with help from producers, Palau-Taiwan Farmers Association, Bureau of Agriculture, Palau Community College – Cooperative Research and Extension, Taiwan Technical Mission, and Western SARE that a) a “Tomato and Blossom Set Spray” containing a cytokinin from seaweed and/or crab shells can be developed and produced locally and b) fish emulsion using the enzyme papain from papaya and citrus peels (to deodorize and provide insecticidal properties) can be developed and produced locally.
Other recommendations/alternatives for consideration:
*Try fine mesh row covers or other strong nets with fine mesh.
*Reduce shade level of the shade clothes and use a finer mesh to keep out aphids and whiteflies.
*Use row covers as sides and roof to reduce wind damage and keep out aphids and whiteflies.
*Leave the roof open/uncovered.
*Try high plastic tunnels.
*Suckers or tip cuttings may be tried to multiply desirable hybrids which show exceptional suitability. All plants from the same package of hybrid seed do not perform equally as they should. On a rare occasion, one stands out.
*Milk dust or milk spray under plastic roof may be tried to reduce bacterial diseases.
*Kaolin clay may be tried to kill aphids, etc.
*Hairy vetch as a no-till mulch crop for tomatoes has been shown to lower pests and increase yields.
*Try 6-8″ of shredded newspaper as mulch to lessen fungal diseases.
*Intercropping with garlic chives, ginger or marigolds may be tried to reduce whiteflies and aphids.
*Aphids have been reduced with derris, neem (sprayed in the evening), soursop, turmeric, yam bean, or flour.
*Whiteflies have been reduced with garlic chives, marigold, ginger, soaps, and milk powder.
*Fruit flies have been reduced with bottle traps, vinegar-honey traps and coconut shell traps.