Guyabano or soursop production
By:Onofre Q. Ballesteros
Greenfields March 1993
For basal fertilization, apply five kilograms of chicken manure or other organic matter, plus 100 grams of 14-14-14 per hole. Mix the fertilizer with surface soil before setting the seedlings.
Depending on soil structure and availability of soil moisture, subsequent fertilization should be on a quarterly or semi-annual basis, 1.e. at the onset of the rainy season and before the dry season starts. Clayey soil needs less frequent application of fertilizer than light or sandy soil.
To enhance rapid vegetative growth and profuse root development, apply a mixture of urea and 14-14-14. The amount of fertilizer depends on age of trees and native soil fertility. For non-bearing trees, 300 to 500 grams of urea per tree per year is recommended. For newly bearing trees, application may range from 750 grams to 1.0 kilogram of 14-14-14 plus 200 to 500 grams of muriate of potash (0-0-60) per tree per year. The use of potash will improve fruit quality. These rates should be increased as the trees become more productive and grow older.
The fertilizer should be applied in holes dug around the base of the trees where most of the feeding roots abound. Cover the fertilizer with soil to prevent loss through volatilization and water run-off.
Remove water sprouts and interlacing branches and prune diseased branches. Protect the cut ends by painting with coal tar, paint or pesticide paste to prevent the entry of disease organisms.
Cultivation and weeding
Shallow-plow the soil to suppress weed growth and prevent brush fires during the dry months. Remove unwanted plants growing around the trees; such plants compete with the trees for nutrients and moisture.
The enormous quantities of organic matter produced in most farms make mulching necessary. Mulching is putting of partially, decomposed farm wastes like rice hull, straw, grass and other materials around the base of trees. Mulch conserves moisture and hinders weed growth. Mulching materials that decompose become organic matter which provides small amounts of plant food to the trees; mulch also improves soil structure.
Pest and disease management
Guyabano is attacked by scales, mealybugs, mites, nest-building ants and twig borers. Regularly spraying pesticides can control these pests. Common diseases- such as antracnose and pink disease – can be minimized by practicing sanitation and spraying the trees with fungicides like manzate, Dithane, copper and sulfur based chemicals. The grower should immediately remove and burn diseased tree parts to prevent the spread of diseases.
The fruits are mature when their skins turn shiny green and the spines are set far apart. The fruits are ripe when they turn slightly yellow.
Bearing trees start flowering in May and June . A second flowering occurs in November and December. Fruits may be harvested four months after flowering/
Gather fully mature but still hard fruits and place them in plastic crates or bamboo baskets. Line the sides of the baskets with newspaper to protect the fruits from bruises.