Integrated stem borer management in smallholder coffee farms in India, Malawi and Zimbabwe
Common Fund for Commodities (CFC) with co-financing and counterpart contributions from national programmes.
International Coffee Organisation (ICO) (Supervisory Body), Natural Resources Institute (NRI) (Assisting Agency), Coffee Board of India, Coffee Research Centre (Chipinge, Zimbabwe), Lunyangwa Research Station (Malawi)
Problem/Issue. The coffee white stem borer (Xylotrechus quadripes) is a widespread pest of coffee in both Africa and Asia, causing severe economic losses.
Damage is caused by the larvae of these cerambycid beetles, which feed just under the bark, which splits to make the stem appear ridged. Later, larvae enter the hardwood and tunnel in all directions, even into the roots.
Infested trees normally have yellow, wilting leaves, and frass ejected by the wood-boring phase and emergence holes can be found on the stems. Severe ring barking of the main roots occurs below ground level, and extends above ground in rejuvenated coffee.
Attack often results in the death of 1- to 2-year-old coffee trees and severe wilting of 3- to 4-year-old trees. Mature trees are not necessarily killed but, especially in Africa, they become susceptible to termite attack, particularly in the absence of irrigation during the dry season. In general, white stem borer infested trees are of poor vigour and yield poorly.
Stem borers have cumulative impact. In addition to crop losses, investment is needed to replace uprooted trees and as these take time to come into production, the effects of borer damage are felt for at least 5 years.
Coffee is currently in oversupply and high consumer stocks exacerbate the situation. Quotas have been abandoned and retention schemes are unlikely to take effect. Overproduction is likely to continue since mechanization of plantations is increasing and keeping prices weak. Smallholder livelihoods are under threat as never before, and if the smallholder farming sector is to survive and compete with large plantations, it needs help to solve problems and develop new strategies.
In such prevailing conditions, smallholder farmers tend to reduce all inputs including pest control efforts, which leads to reduced quality and quantity, thus further affecting their economic position. The best response to the situation, however, is to concentrate on increasing quality, and adopt tactics that help reduce inputs of dangerous and costly chemicals. Such a strategy will also facilitate entry to new markets, which pay more for environmentally friendly, sustainably produced coffees. This project aims to help them achieve this, and protect them from any future claims that they are insensitive to the increasing environmental awareness of consumer countries.
Measures to Date. Current management strategies are generally ineffective, or rely on undesirable chemical applications. Cultural control methods include uprooting and burning infested trees, treating the stems during the oviposition period to kill or dislodge eggs and young larvae, catching and killing adults during their period of activity, and maintaining shelter belts in order to shade the coffee bushes, as plants exposed to sunlight are more at risk.
Chemical control includes treatment of stems and primary branches with BHC to reduce the incidence of attack. Biocontrol of X. quadripes in Vietnam during the 1920s involved mass-releases of the two most easily reared parasitoids found in plantations (Doryctes strioliger and Sclerodermus domesticus). The resultant increase in parasitism rates was not maintained after releases ceased. The work was abandoned owing to the high cost of developing a continuous mass rearing programme.
Current management techniques under trial on a local basis include:
Project Activities. The aim of this project is to develop and implement new ways of controlling stem borers, focusing on methods that are designed to be environmentally friendly, non-toxic, and cheap enough to be within the reach of smallholder coffee farmers. This will enable farmers to more sustainably maintain their coffee without recourse to expensive replanting or control measures.
As white stem borer is the major constraint to the production of arabica coffee in India, Zimbabwe and Malawi, there is urgent need to evolve an effective integrated management package. Immediate objectives are therefore to:
Specific objectives involve:
Achievements So Far
The CFC approved funding for the project totalling US$2.26 million in October 2001 (of total project value of US$3.1m), subject to final signing of Project Agreements. This has now been completed and the project commenced in mid-July 2002.
An inauguration workshop will be held, most probably in India, in September 2002.
Dr. Peter Baker (International
Start: July 2002