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Pests and Diseases
Photo : ICRISAT
 
 

Integrated pest management places a powerful, eco-friendly tool in the hands of poor dryland farmers. In many cases the results are comparable and frequently better than those achieved by farmers who use chemicals alone.

US $ 7 billion - Annual economic damage caused by insect pests, fungi, viruses, and weeds in legume and cereal crops alone

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As climate change takes hold, farmers and scientists deploy new strategies for controlling pests and diseases

Controlling pests and diseases is a centuries-old problem. Farmers know it well and have developed a number of strategies to keep ahead of fast-emerging biotic stresses.  The traditional practices that farmers’ use can be highly effective, but conditions are shifting as climate change and globalization speed up the evolution and emergence of new pest and disease variants.

Agricultural science has amassed a series of tools that farmers can use to monitor, track and control pests and diseases. Even so, the need for effective, integrated control measures increasingly urgent.

Scientists estimate that food crops produced in the semi-arid tropics are adversely affected by more than a thousand species of insect pests, fungi, viruses, and weeds. Economic damage in legume and cereal crops alone now exceeds US$ 7 billion annually. Although agro-chemicals offer effective controls, modern pesticides are too expensive for farmers and most lack the training to use them safely and effectively.  

To help farmers adapt, scientists have assembled simple-to-use control practices that offer producers the means to prevent crop losses with minimal use of chemical pesticides. It is a demand-driven approach known as integrated pest management or IPM.

A farmer-scientist partnership

IPM is basically a partnership that brings together farmers’ traditional understanding of land and crops with researchers’ technical knowledge and expertise. The scientists’ job is to make available the genetic resistance found in improved varieties – limited as it is – along with bio-pesticides, natural enemies, and improved agronomic practices. Farmers drive the process by evaluating the new technologies and ultimately by deciding how and when to use them.

In the hands of farmers, IPM can be a powerful, eco-friendly tool. In most cases the results are comparable to – and frequently better than – those achieved by using agro-chemicals alone. The principle behind IPM is to control pest problems without damaging the land and minimizing the exposure of farmers and their families to dangerous chemicals. IPM is not anti-chemical. In fact, chemicals are an important component of integrated pest management, but their use is kept to a minimum and they are deployed mainly as a complement to more natural control measures.

The principal components of an effective IPM program are host plant resistance, natural enemies, bio-pesticides, and cultural practices, combined with minimal use of agro-chemicals. 

Pest problems in ICRISAT mandate crops: Priority areas of research

Insect pests, diseases, and Striga are serious constraints to increasing production, productivity, and utilization of ICRISAT’s mandate crops (sorghum, pearl millet, chickpea, pigeonpea, and groundnut) in the semi-arid tropics. Crop losses due to these pests have been estimated at over US$ 7.4 billion annually. While Helicoverpa control is heavily based on insecticides, chemical control of shoot and panicle feeding insects on cereals is beyond the reach of resource poor farmers in the SAT regions in Asia, Africa, and Latin America. Current sensitivities about environmental pollution, human health, and pest resurgence are a consequence of improper use of synthetic pesticides. Host plant resistance, natural plant products, bio-pesticides, natural enemies, and agronomic practices offer a potentially viable option for integrated pest management. They are relatively safe for the non-target organisms and human beings. Modern biotechnological tools such as marker-assisted selection, genetic engineering, and wide hybridization to develop crop cultivars with resistance to insect pests and diseases will have a great bearing on future pest management programs. Insect and disease modeling, decision support systems, and remote sensing would contribute to up scaling and dissemination of the IPM technologies.

Current research projects in biotechnology, crop improvement, and natural resource management focus on the major pests such as pod borers (Helicoverpa, Maruca, and Melanagromyza), Fusarium wilt, and sterility mosaic in pigeonpea; Helicoverpa, Wilt, Ascochyta, and Botrytis gray mold in chickpea; Rosette virus, foliar diseases, aflatoxins, and leaf miner in groundnut; Striga, grain molds, shoot fly, stem borers, midge, and head bugs in sorghum; and downy mildew, stem borer and head miner in pearl millet. IPM promotion and capacity building of partners are significant components of research at ICRISAT.

Important diseases of ICRISAT mandate crops and potential interventions.

Crop

Disease

Distribution

AP

BC

HPR

CC

CPB

WH

MAS

GE

Sorghum

Grain molds

Asia, Africa

*

-

*

-

*

*

*

Leaf diseases

Asia, Africa

*

-

**

-

**

-

*

Striga

Asia, Africa

*

-

**

-

**

-

**

Pearl millet

Downy mildew

Asia, Africa

*

-

***

-

***

*

**

Ergot

Asia, Africa

*

-

**

-

*

-

-

Smut

Asia, Africa

-

-

**

-

*

-

-

Chickpea

Wilt

Asia

*

*

***

*

***

-

*

AB

Asia, Africa

*

*

**

**

**

*

**

BGM

Asia

*

*

**

**

**

*

**

Pigeonpea

Wilt

Asia, Africa

*

*

***

-

**

-

*

SM

Asia

*

-

***

-

*

-

*

Groundnut

Foliar diseases

Asia, Africa

-

-

***

***

**

-

***

Aflatoxin

Asia, Africa

**

**

*

*

*

*

*

Rossette

Africa

*

-

**

-

-

**

**

Stem necrosis

Asia

-

-

**

-

-

**

**

AP = Agronomic practices; BC = Biological control; HPR = Host plant resistance; CPB = Conventional plant breeding; WH = Wide hybridization; MAS = Marker-assisted selection; GE = genetic engineering; CC = Chemical control; AB = Ascochyta blight; BGM = Botrytis gray mold; SM = Sterility mosaic; - = No potential; *, **, *** = Low, medium, and high potential, respectively.

IPM research at ICRISAT: Progress made
IPM research in ICRISAT has involved the following:
  • Refining screening techniques, identifying sources of resistance, and studying mechanisms and inheritance of resistance
  • Introgression of insect resistance genes into high-yielding cultivars
  • Identifying and integrating IPM components (cultural, bio-control, HPR, and synthetic pesticides) for viable pest management
  • Marker-assisted selection and genetic engineering for resistance to insect pests
  • Exploiting germplasm and wild relatives for resistance to insect pests
  • Assessing the biosafety of genetically modified crops to the non-target organisms.

Photo: ICRISAT
Scientists have identified sorghum genotypes that farmers can grow in fields infested with Striga, aka “witch weed”, a parasitic plant that causes significant damage to dryland cereal crops across Sub-Saharan Africa and large parts of Asia. Providing an effective, eco-friendly control for Striga could boost productivity dramatically and reduce the burdens placed on female farm labor.
Photo: ICRISAT
Research has shown that several fungal and bacterial strains provide effective control of Aspergillus flavus in groundnut. The results of this work have important implications for human health and the export potential for the produce of groundnut farmers throughout the semi-arid tropics.
Photo: ICRISAT
Soilborne diseases (stem rot and collar rot) affect the groundnut plant.
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