Overcoming the Constraints of Tropical Tomato Production Through Shade Netting and Other Methods

*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.