Growing Chemical-Free Vegetables
Non-chemical approaches against soil-borne diseases in vegetables
Soil-borne diseases are a group of plant pathogens that are highly destructive to crops and are difficult to control. These diseases result from a reduction of biodiversity of soil organisms. Restoring beneficial organisms that attack, repel, or otherwise antagonize disease-causing pathogens will render a soil disease-suppressive. Plants growing in disease-suppressive soil resist diseases much better than in soils low in biological diversity. Beneficial organisms can be added directly, or the soil environment can be made more favorable for them through use of compost and other organic amendments.
Today, alternative measures to chemicals are available in controlling these soil-borne diseases in vegetable production. Recent research in sustainable management of soil amendments have been successfully demonstrated in suppressing soil-borne pathogens and enhancing plant growth.
FFTC, in partnership with the Royal Project Foundation and Maejo University, Thailand, sponsored a training workshop and field demonstration on non-chemical approaches against soil-borne diseases, to address the growing concern among people worldwide about the quality of their food and the conservation of the environment. The activity served as a venue to exchange and promote practical knowledge and technology on the non-chemical management of soil-borne diseases to achieve sustainable vegetable production, with less dependency on synthetic pesticides and fungicides and lesser risk of soil, water and air pollution.
Management of Diseases with Agricultural Wastes
Agricultural wastes such as rice straw, rice hull, peanut husk, corn cob, bagasse, rape-seed pomace, castor seed pomace, tree bark, mushroom growth medium waste, and shrimp shell powder are widely used in land reclamation and in horticultural crop production. They benefit the crops by improving soil fertility, increasing soil organic matter and, in many instances, reducing the incidence of plant diseases.
During the past 25 years, several excellent container media, organic amendments and plant extract products have been formulated by using agricultural wastes and fertilizers for the management of crop diseases in Taiwan. Most of the formulated products were designed to maximize the harmful effect on target pathogens and maintain soil fertility with minimal negative impacts on the agroecosystem.
Use of Biocontrol and Biofertilizer in Crop Production
Biocontrol refers to a reduction of nematode populations accomplished through the action of living organisms other than nematode-resistant host plants, which occurs naturally or through the manipulation of the environment or the introduction of antagonists. In Taiwan, chitin amendments, particularly Streptomyces saraceticus, was found to enhance the activity of indigenous soil microbes and considered a good biocontrol agent for plant parasitic nematode problems
In Japan, biological control of plant diseases has received considerable attention from plant pathologists, farmers, and consumers alike. Commercialization of biologically-based pesticides, such as microbial pesticides, are becoming increasingly popular and often are safer than traditional chemical pesticides.
In other countries, management of soil-borne diseases are done through integrated control measures. It considers the basic principle in agriculture that healthy soils support healthy and profitable crops. Reducing input of fertilizers and agro-chemicals to soil is the first step to recover soil health, while sustainable cultural practices and biological means will facilitate the control of soil-borne diseases.
Field Demonstration
As a collaborative undertaking among FFTC, the Royal Project Foundation and the Maejo University of Thailand, a field demonstration on the use of non-chemical management to control soil-borne diseases for some selected vegetables was established in Chiang Mai, Thailand which the participants had the opportunity to visit. The field demonstration aimed to test the effectiveness of non-chemical control using biological products against pathogenic diseases and in enhancing vegetative growth of crops.
Conclusion
In view of the rapid changing and globalizing food economy, and as a result of the worldwide concern and commitment among stakeholders about food production and security, food safety and quality, and environmental sustainability of agriculture in the Asian and Pacific region, new agricultural practices using non-chemical approaches must be promoted. The common mission is how to balance human need for food security and economic development, with the need for livelihood security, environmental conservation, and social responsibility.
Index of Images
Figure 1 Soil-Borne Diseases: Fusarium Wilt (below Left) and Phytophthora Diseases (below Right)
Figure 2 Field Tour of Demonstration Plots of the Royal Project Foundation, Thailand
