Cultural management of pest infestation

Watching somewhere

An integrated approach to pest management where the role of pesticides is minimal is possible when the farmer is aware of the biology and environmental responses of key organisms in the farm ecosystem.

Cultural management practices, if applied properly, can help prevent pest breakout. Improper or non-application of specific cultural management practices may predispose the crops to pest infestation. The objective is to create a microenvironment in the farm which favors the crop and deters most pests.

SITE SELECTION

1. Rainfall. The distribution of rainfall affects pest populations. For instance, the coffee berry borer problem is difficult to control in areas with well-distributed rainfalls primarily because the spread-out harvest period allows overlapping generations of this pest. And, the mango anthrachnose problem also makes mango cultivation difficult in such areas.

2. Humidity. One of the reasons why scales are not a problem during the rainy season is the proliferation of entemogenous fungi which parasitize the scale insects. Coffee rust is also inhibited in humid areas. However, most other fungi and bacteria thrive in humid locations.

3. Temperature. The incidence of citrus scab increases with elevation. In contrast, the coffe rust pathogen becomes more destructive in the lower elevations.

4. Soil pH. Acid soils have been associated with increased incidence of Panama wilt of banana and abaca.

5. Drainage. Waterlogging predisposes the plants to root rot pathogens. The high humidity in waterlogged banana plantations predisposes the plants to leaf pathogen infection.

6. Location. It is wise to avoid planting in areas where major diseases of the choice crop species abound. For example, planting citrus in the general Batangas area would be tantamount to committing suicide because of the endemic citrus pests and pathogens (viruses) in the area. The same goes for the ring spot virus of papaya which is already endemic to the Laguna, Batangas and Cavite areas.

STANDING VEGETATION

The current vegetation in an area targetted for planting with perennial crops should be evaluated in terms of alternate host potential. For example, wild Heliconia are alternate host plants of the pineapple mealybug. This is particularly important, especially if the standing plants are old ones scheduled for replanting. In such cases, the inoculum load (disease incidence) should be considered before deciding on specific planting materials.

VARIETAL SELECTION

If possible, use resistant cultivars. For example, saba banana is practically immune to the corn weevil. The S 795 and S 288 arabica varieties are highly resistant to coffee nust.

NURSERY PRACTICES

The nursery should be isolated from potential sources of inoculum. Seed bed media should be sterilized if not replaced regularly. The seed bed should be well-drained in order to prevent damping off.

Use pest-free propagules in the nursery. Periodic spraying with pesticides should be able to keep down the incidence of general foliage feeders and pathogens. In case of nematode infestation, nematicides should be applied to each plasticbagged seedling.

CLEARING PROCEDURES

Remove remnant stumps if crops (like rubber) highly susceptible to rots are to be planted. Burning as a method of clearing sterilizes the first 5-10 cm top soil layer and rids them of various weed propagules and soil borne insect pests and pathogens. It also eliminates infected plants.

PLANTING METHODS

1. Time of planting. Plant abaca and banana just before the rainy season so that the wounds on the propagules can heal before the wet soil condition which will favor pathogens. This is known as field-curing. This is also practiced in the case of kakawate cuttings planted directly to the field. in pineapple, slips and suckers are allowed to air-dry so that the butt end will dry up and become less susceptible to pathogens.

2. Planting density. High density systems result in greater humidity immediately around each plant.
This leads to higher black lead streak incidence in banana and greater pod rot incidence in cacao.

3. Cropping system. Theoretically speaking, it is not advisable to mix crop species which share the same major insect pests/pathogens. In some crop combinations like rubber and cacao, this premise has been shown to be true; but in other cases, like in coconut, papaya, pineapple combinations, this principle has not been verified to be operant. All these crops are attacked by
Phytophthora palmivora.

4. Tillage practices. Inter-row cultivation to control weeds in mature perennial crops is unpopular because it leads to root injury which can increase incidence of rootrots.

5. Shade management. Shade increases humidity which predisposes the plants to fungal and bacterial infestations. However, plants exposed to full sunlight are predisposed to mistle toe and insect attacks.

6. Cover cropping. Cover cropping favors hyper parasite wasp populations that attack slug caterpillars. However, they may act as alternate host plants. For example, Crotollaria is host to coffee berry borer. Some cover crop species are useful as follow crop for nematode-infested pineapple plantations.

7. Mulching. Mulching has been observed to reduce nematode populations putatively due to its favorable effect on Paecilomyces lilacinus.
However, if placed too closely on the trunk, it may enhance termite/wood beetle infestation.

8. Pruning and thinning. A major function of pruning and thinning operations is the elimination of infected organs or trees from the plantation.
Pruning thinning also help open up the canopy not only to eliminate shaded/humid pockets inside but also to facilitate the penetration of pesticidal sprays.

9. Fertilizer practices. A well-nourished plant can withstand infection/lnfestation better than weak plants. Overbearing dieback is common in many perennial crops that were not properly supported with water and nutrients. High N fertilization has been shown to reduce the effects of the shot hole borer in tea. Chlorine fertilization reduces the incidence of coconut leaf spots.

10. Irrigation. Drought predisposes plants to pathogen attack in the subsequent rainy period.

11. Harvesting procedures. The complete removal of fruits for at least three to four months in coffee and cacao plantations can control the berry borer and the pod borer problems of the respective crops. Harvesting fruits at the mature green stage and preventing the fruits from ripening in the plantation help reduce fruit fly infestation. In all crops, it is advisable to remove and burn/bury infested fruits during the harvesting operation.