Earthworm-farmer friendship, redefined

Earthworms suppress fungal diseases in the soil © pfly (Flickr, CC BY-SA 2.0 license)

Earthworms are known as farmers’ best friends because of the multitude of services they provide that improve soil health and consequently plant health. The density of earthworms in the soil is considered to be a good indicator of a healthy soil because they improve many soil attributes like structure, water holding capacity, moisture content etc., and also increase nutrient availability and degrade pesticide residues. As scientists understand these ‘ecosystem services’ provided by earthworms, they discover that this earthworm-farmer friendship is a lot deeper than previously imagined! Continue reading

Epigenetics – a new dimension to understanding plant disease

Coast live oak showing sudden oak death symptoms (Credit: Joseph O’Brien, USDA Forest Service,

The history of diseases that have affected a plant can determine the ability of its progeny to cope with similar diseases. Studies have revealed that, in many cases, progeny of a plant that was diseased develops tolerance to similar stresses in just a few generations, far too quick to be explained by chance mutations. It is here that scientists believe epigenetic mechanisms play a role. Continue reading

Quorum-sensing disruption, a new tool for disease management?

A new study by Chernin et al. has found that volatile organic compounds produced by certain Plant Growth Promoting Rhizobacteria (PGPR) can disrupt bacterial cell-cell communication (quorum sensing) in a number of plant pathogens including Agrobacterium, Chromobacterium, Pectobacterium and Pseudomonas. Application of PGPRs could in future be used as a new disease management strategy.

Continue reading

Managing deoxynivalenol (DON) contamination in Fusarium head blight affected wheat

Fusarium head blight on wheat. Mary Burrows, Montana State University,

Fusarium spp. (particularly F. graminearum) causes a serious disease on wheat called Fusarium head blight. The disease affects the quantity and quality of grain and under favorable weather conditions can cause more than 45% yield losses. Symptoms include the appearance of tan or brown discoloration on spikelets resulting in white, shriveled kernels. Such infected kernels are often contaminated with mycotoxins nivalenol, zearalenone and more commonly deoxynivalenol (DON). This mycotoxin is very toxic to humans and animals and the maximum tolerable daily intake is set at 1 ug/kg body weight.

Two recent studies in Japan and USA provide new insights to the timings of mycotoxin accumulation in wheat and strategies for separating infected kernels from healthy kernels during harvest.

Continue reading

Understanding and managing aflatoxicosis outbreaks in Kenya

Aspergillus ear rot on corn. USDA APHIS PPQ Archive,

Aspergillus flavus and A. parasiticus are important fungal pathogens that infect a wide range of cereals, oil seeds and nuts. They produce toxic metabolites called aflatoxins (mycotoxins with carcinogenic and teratogenic properties) that can contaminate food products. Although strictly regulated around the world, aflatoxin contamination in developing countries is poorly regulated. In addition, limited management options and lack of agricultural resources have led to repeated outbreaks of acute aflatoxicosis, fatal to many. Two recent studies on strains of A. flavus may provide a new route for aflatoxin management.

Continue reading

Improved understanding of Striga resistance in rice

Striga infected field. USDA APHIS PPQ Archive,

A group of scientists from the Netherlands, UK and Africa have studied upland NERICA rice cultivars to identify those that exhibit multi-level striga resistance. In two separate research papers, the 18 NEw RICe for Africa (NERICA) cultivars and their parents were screened for pre- and post- attachment striga resistance. One particular cultivar NERICA 1 was shown to possess high levels of both these types of resistances.

Continue reading