Project Activities

Vine weevil larvae / © FhF GreenMedia

The economic losses from crop pests, diseases and weeds are presumed large and worthy of sizable R&D support; witness, for example, the April 2, 2008 $26.8 million commitment by the Gates Foundation to combat wheat rust disease and protect resource-poor farmers. What is not known is the magnitude and incidence of the losses involved in one specific pest or disease on one crop versus the same biotic stress on a different crop or different stresses on the same crop. This makes it hard to discern the investment priorities to give research aimed at a specific disease-crop complex versus other disease-crop complexes, or the priority to give research targeted to one agroecology versus another for a given crop production problem. In addition, biotic stressors often raise the risk of crop failures, which often means subsistence farmers shy away from the use of modern crop varieties (that might, on average be higher yielding), in favor of landraces presumed more robust in the face of a range of biotic (and abiotic) crop stressors. These risk-reward trade-offs are crucial determinants of the rate of uptake of new crop and management technologies.

Leaf hopper / © Arlindo Silva

Recognizing these constraints, and in the absence of sufficiently comprehensive and reliable data, HarvestChoice and its partners are making a major effort to assess the crop production and economic impacts of biotic stressors.

Objectives

The objective is to develop comparable assessments of the payoffs from "solving" specific pest, disease and weed problems in ways that support prioritizing research investments designed to tackle these problems. Importantly, and in addition, the approach to modeling and measuring the effects of biotic constraints is being done in ways that maximize comparability with HarvestChoice assessments of the payoffs to research designed to address important abiotic constraints such as drought and low soil fertility. This makes it possible to assess the opportunity costs (research benefits forgone) of choosing to invest in one line of research versus another, thereby appraising investors of the economic trade-offs involved in funding competing demands on scarce research dollars.

HarvestChoice and its partners are producing new methods, procedures and tools to address the data problems and to develop an extensive array of pest, disease and weed distributions at a degree of spatial resolution that is sufficient to inform bio-economic modeling and technology impact assessments. This line of research will enable HarvestChoice and others to place plausible and spatially explicit economic values on the gains from solving specific pest, disease and weed problems.

A Brief Chronology of Activities

• Much of the biotic stress methodology has resulted from various HarvestChoice consultations, the first of which was an April 2007 Expert Consultation at the University of Minnesota. This meeting involved a targeted sub-set of scientists who also attended the Genes, Seeds, Plots, Models and The Poor Roundtable. The expert consultation resulted in an initial list of crops and pests that are presumed to result in economically “significant” reductions in crop yields, especially in sub-Saharan Africa. Options for modeling the spatial occurrence of biotic stressors were considered. One option was NAPPFAST , the other, and the one chosen for the current modeling efforts of HarvestChoice is CLIMEX. This choice was revisited, reconsidered and reconfirmed after HarvestChoice associates attended a June 2007 Science Panel Workshop on Pest Risk Mapping sponsored by the USDA Animal and Plant Health Inspection Service.
• A few days after the APHIS workshop, HarvestChoice and partner organizations (CIMMYT , IFPRI and the University of Minnesota ) hosted a weeklong "proof of concept" workshop at CIMMYT headquarters in El Batan, Mexico. A number of draft pest and disease distribution maps were produced at this meeting, some of which are presented below.
• The paucity of pest, disease and weed data of sufficient granularity to develop the spatially referenced occurrence data required to support spatially explicit modeling methods that assess the economic benefits from reduced pest, disease and weed problems spurred a search for a rapid, but replicable and reasonably reliable, survey technique to reveal and codify occurrence data. Recognizing much of these data are held as tacit not published knowledge, often by those with local expertise, an on-line survey instrument dubbed  V-GET™ (Virtual Georeferenced Elicitation Tool) was developed and is presently in use by HarvestChoice and a range of project partners to build better maps of presumptively important pest, disease and weed occurrences worldwide.