2009 Annual Report for FW08-008
Overcoming the Constraints of Tropical Tomato Production Through Shade Netting and Other Methods
Summary
SUMMARY
The demand for tomatoes in Palau is quite high. Farmers are keen to grow tomatoes but are hesitant due to many failed attempts including the following: hydroponics, which failed due to contamination; high tunnels, which failed due to excessive heat, humidity, and wind; open fields, which failed due to disease; high risk, high cost, and the prevalence of blossom end rot, which failed due to calcium deficiency; disease, caused partially by overwatering; cracked fruit, which failed due to frequent heavy rains; and other losses due to sun scalding, fruit flies, and poor fruit sets
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 shade houses and were vectors for disease.
Due to the rapid build-up of algae and fungus in the shade houses, 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 these diseases, for reintroduction of diseases was rapid through air and water.
Tomato production by other producers increased in Palau after the first harvest of the project. 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% if current constraints are overcome.
OBJECTIVES
• 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.
METHODS
We began by surveying the site, mapping it, and laying it out. We then solarized the site to kill fruit fly larvae and other pests. We used a shredder to produce materials for mulching and composting, and we installed shade netting, cages, mulch and EarthBoxes and then direct seeded. For comparison, some seeds were started in pots and transplanted out.
We participated in the subregional Western SARE Conference in Kona. The farmers’ knowledge base was expanded by:
1. Participation in the PDP meeting, the ACF (American Culinary Federation) Farmer-Chef Conference and the 18th Annual Hawaii International Tropical Fruit Growers Conference
2. Observing what works in Hawaii
3. Sourcing technical advisors/specialists
4. Witnessing innovative marketing to visitors
5. Learning from tours of successful Western SARE projects, farms, and value adding facilities
We also produced a pamphlet on growing tomatoes under shade netting and planted tomatoes in an open field using conventional methods as a comparison.
RESULTS
Our screening kept out most pests, with no fruit flies attacking the tomatoes under the shade netting, though flies and aphids found a way into the shade houses. The shade netting also prevented losses due to sunscald and was able to release excessive heat, humidity, and wind. Due to the rapid build-up of algae and fungus in the shade houses, we theorized that 50% shade netting does not let in enough sun to keep algae and fungus at bay. We replaced the 50% shade netting on the roof with netting ranging from 25% to 35%.
The use of tomato cages was abandoned due to the high prevalence on nearby farms of a plant killing fungus associated with partially decomposed organic materials. We did mulch and amend the soil with burnt eggshells, lime, gravel, and coral sand to reduce 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.
We found that Enz/Rot Blossom End Rot Concentrate worked well in eliminating end rot. Tomato Set Spray worked well at improving fruit setting, and Bull’s-Eye Bioinsecticide did not reduce the white flies and aphids, nor did Neem-Away prevent or reduce fungal infections.
Tomatoes planted out in open field using conventional methods and inputs experienced the same problems as those under shade netting, but also experienced sunscald, cracking, and cat face. Sevin and Malathion reduced the number and frequency of infestation of white flies and aphids resulting in fewer diseases, more production and a slight economic profit. This light economic profit is offset by loss of bees and other pollinators and predators of pests.
CHALLENGES/OPPORTUNITIES
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 a solarized area bore a good crop and died prematurely due to drowning, cooking, and an unidentified white fungus. Some plants drowned due to poor drainage of the soil and plentiful rain, dew, fog, and other precipitation. We tried to alleviate this problem through incorporation of more organic matter, sand, gravel, variety selection, and drainage ditches.
Additionally, high winds on hot days resulted in the top layer of soil drying out while bottom layers remained moist. This resulted in a scarred, weak patch of stem at ground level interfering with the intake of nutrients and occasionally breakage of the stem at ground level.
Tomatoes planted in four and five-gallon containers in shade houses 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. We are trying to lessen this problem through sterilizing the whole shade house, sterilization of all materials used, and variety selection.
BENEFITS/IMPACTS OF AGRICULTURE
The project will increase overall farm production levels by about 12% if current constraints are overcome. The project maintained and enhanced the quality and productivity of the soil through the use of a shredder that produced organic materials for mulching, composting, and incorporation into the soil. The project also maintained the quality of groundwater by using organic fertilizers, thus avoiding artificial chemicals that pollute water, and it protected the health of the farm family and farm hands by using organic fertilizers and by using screening to keep out pests, thus requiring no inputs of toxic materials.
PRODUCER ADOPTION
Tomato production by other producers increased in Palau after the first harvest of this project. We theorize this is due to a few other producers adopting some of the methods used.
REACTIONS FROM PRODUCERS
Comments we received about our project include the following:
• “The shade house is good for the environment and relatively cheap and easy to put up.”
• “Success is dependant more on variety than methods. Test as many varieties as possible.”
• “The shade netting filters too much sunlight.”
• Forget tomatoes; it is a foreign crop and will not yield a long-term profit.”
• “Switch to growing and selling native ornamentals and traditional healing plants.”
RECOMMENDATIONS AND NEW HYPOTHESIS
• Reduce shade netting to 25-35%., which will reduce algae and fungi and result in greater production.
• For control of white flies and aphids, try weekly spraying of seaweed and fish emulsion. If neither provides effective control, try derris and Barringtonia asiatica. Both are locally available insecticidal plants.
• Adding gravel to the bottom of containers, adding seaweed to the potting soil, and doubling the drainage area will reduce algae and fungi, improve disease resistance, and improve production.