Dec. 16, 2018
Keeping QualityRipe guavas bruise easily and are highly perishable. Fruits for processing may be harvested by mechanical tree-shakers and plastic nets. For fresh marketing and shipping, the fruits must be clipped when full grown but underripe, and handled with great care. After grading for size, the fruits should be wrapped individually in tissue and packed in 1 to 4 padded layers with extra padding on top before the cover is put on. They have been successully shipped from Miami to wholesalers in major northern cities in refrigerated trucks at temperatures of 45° to 55° F (7.22°-12.78° C). It is commonly said that guavas must be tree-ripened to attain prime quality, but the cost of protecting the crop from birds makes early picking necessary. It has been demonstrated that fruits picked when yellow-green and artificially ripened for 6 days in straw at room temperature developed superior color and sugar content.
Guavas kept at room temperature in India are normally overripe and mealy by the 6th day, but if wrapped in pliofilm will keep in good condition for 9 days. In cold storage, pliofilm-wrapped fruits remain unchanged for more than 12 days. Wrapping checks weight loss and preserves glossiness. Unwrapped 'Safeda' guavas, just turned yellow, have kept well for 4 weeks in cold storage at 47° to 50° F (8.33°-10° C) and relative humidity of 85-95%, and were in good condition for 3 days thereafter at room temperature of 76° to 87° F (24°-44° C).
Fruits coated with a 3% wax emulsion will keep well for 8 days at 72° to 86° F (22.2°-30° C) and 40 to 60% relative humidity, and for 21 days at 47° to 50° F (8.3°-10° C) and relative humidity of 85-90%. Storage life of mature green guavas is prolonged at 68° F (20° C), relative humidity of 85%, less than 10% carbon dioxide, and complete removal of ethylene.
Researchers at Kurukshetra University, India, have shown that treatment of harvested guavas with 100 ppm morphactin (chlorflurenol methyl ester 74050) increases the storage life of guavas by controlling fungal decay, and reducing loss of color, weight, sugars, ascorbic acid and non-volatile organic acids. Combined fungicidal and double-wax coating has increased marketability by 30 days.
Australian workers report prolonged life and reduced rotting in storage after a hot water dip, but better results were achieved by dipping in an aqueous benomyl suspension at 122° F (50° C). Higher temperatures cause some skin injury, as does a guazatine dip which is also a less effective fungicide.
Fruits sprayed on the tree with gibberellic acid 20-35 days before normal ripening, were retarded nearly a week as compared with the untreated fruits. Also, mature guavas soaked in gibberellic acid off the tree showed a prolonged storage life.
Trials at Haryana Agricultural University, Hissar, India, showed that weekly spraying with 1.0% potassium sulfate-1.6 gals (6 liters) per tree-beginning 7 days after fruit set and ending just before harvesting at the pale-green stage, delays yellowing, retains firmness and flavor beyond normal storage life.
Food technologists in India found that bottled guava juice (strained from sliced guavas boiled 35 minutes), preserved with 700 ppm SO2, lost much ascorbic acid but little pectin when stored for 3 months without refrigeration, and it made perfectly set jelly.
Pests and DiseasesGuava trees are seriously damaged by the citrus flat mite, Brevipa1pus californicus in Egypt. In India, the tree is attacked by 80 insect species, including 3 bark-eating caterpillars (Indarbella spp.) and the guava scale, but this and other scale insects are generally kept under control by their natural enemies. The green shield scale, Pulvinaria psidii, requires chemical measures in Florida, as does the guava white fly, Trialeurodes floridensis, and a weevil, Anthonomus irroratus, which bores holes in the newly forming fruits.
The red-banded thrips feed on leaves and the fruit surface. In India, cockchafer beetles feed on the leaves at the end of the rainy season and their grubs, hatched in the soil, attack the roots. The larvae of the guava shoot borer penetrates the tender twigs, killing the shoots. Sometimes aphids are prevalent, sucking the sap from the underside of the leaves of new shoots and excreting honeydew on which sooty mold develops.
The guava fruit worm, Argyresthia eugeniella, invisibly infiltrates hard green fruits, and the citron plant bug, Theognis gonagia, the yellow beetle, Costalimaita ferruginea, and the fruit-sucking bug, Helopeltis antonii, feed on ripe fruits. A false spider mite, Brevipalpus phoenicis, causes surface russeting beginning when the fruits are half-grown. Fruit russeting and defoliation result also from infestations of red-banded thrips, Selenothrips rubrocinctus. The coconut mealybug, Pseudococcus nipae, has been a serious problem in Puerto Rico but has been effectively combatted by the introduction of its parasitic enemy, Pseudaphycus utilis.
Soil-inhabiting white grubs require plowing-in of an approved and effective pesticide during field preparation in Puerto Rico. There are other minor pests, but the great problems wherever the guava is grown are fruit flies.
The guava is a prime host of the Mediterranean, Oriental, Mexican, and Caribbean fruit flies, and the melon fly-Ceratitis capitata, Dacus dorsalis, Anastrepha ludens, A. suspensa, and Dacus cucurbitae. Ripe fruits will be found infested with the larvae and totally unusable except as feed for cattle and swine. To avoid fruit fly damage, fruits must be picked before full maturity and this requires harvesting at least 3 times a week. In Brazil, choice, undamaged guavas are produced by covering the fruits with paper sacks when young (the size of an olive). Infested fruits should be burned or otherwise destroyed. In recent years, the Cooperative Extension Service in Dade County, Florida, has distributed wasps that attack the larvae and pupae of the Caribbean fruit fly and have somewhat reduced the menace.
In Puerto Rico, up to 50% of the guava crop (mainly from wild trees) may be ruined by the uncontrollable fungus, Glomerella cingulata, which mummifies and blackens immature fruits and rots mature fruits. Diplodia natalensis may similarly affect 40% of the crop on some trees in South India.
Fruits punctured by insects are subject to mucor rot (caused by the fungus, Mucor hiemalis) in Hawaii. On some trees, 80% of the mature green fruits may be ruined.
Algal spotting of leaves and fruits (caused by Cephaleuros virescens) occurs in some cultivars in humid southern Florida but can be controlled with copper fungicides. During the rainy season in India, and the Province of Sancti Spiritus, Cuba, the fungus, Phytophthora parasitica, is responsible for much infectious fruit rot. Botryodiplodia sp. and Dothiorella sp. cause stem-end rot in fruits damaged during harvesting. Macrophomina sp. has been linked to fruit rot in Venezuela and Gliocladium roseum has been identified on rotting fruits on the market in India.
In Bahia, Brazil, severe deficiency symptoms of guava trees was attributed to nematodes and nematicide treatment of the soil in a circle 3 ft (0.9 in) out from the base restored the trees to normal in 5 months. Zinc deficiency may be conspicuous when the guava is grown on light soils. It is corrected by two summer sprayings 60 days apart with zinc sulphate.
Wilt, associated with the fungi Fusarium solani and Macrophomina phaseoli, brings about gradual decline and death of undernourished 1-to 5-year-old guava trees in West Bengal. A wilt disease brought about by the wound parasite, Myxosporium psidii, causes the death of many guava trees, especially in summer, throughout Taiwan. Wilt is also caused by Fusarium oxysporum f. psidii which invades the trunk and roots through tunnels bored by the larvae of Coelosterna beetles. Anthracnose (Colletotrichum gloeosporioides) may attack the fruits in the rainy season. Pestalotia psidii sometimes causes canker on green guavas in India and rots fruits in storage.
Severe losses are occasioned in India by birds and bats and some efforts are made to protect the crop by nets or noisemakers.