Disease pathogens and soil-inhabiting insects in cereals
Unpredictable weather and machinery breakdowns are just a few of the many noticeable challenges growers regularly encounter. Some obstacles affecting productivity, like soilborne diseases and insects, are not as obvious as they lurk below the ground’s surface. In cereal crops, Fusarium, Pythium and Rhizoctonia attack seeds and roots, stealing valuable nutrients and resources needed to produce high-quality crops.
Possessing the potential to act synergistically with soilborne diseases, nematodes, and soil-inhabiting insects, like wireworms, also feed on and damage plant roots. This interaction leaves crops susceptible to more disease, other environmental stressors and ultimately, reduced yields. To help ensure vigorous crop growth, it is critical to understand the challenges impacting root health and stand establishment and determine viable, protective solutions.
Over the last 11 years, Tim Paulitz, Ph.D.,research plant pathologist, USDA-ARS in Pullman, Wash., and his research associate, Kurt Schroeder, Ph.D. at Washington State University, have been closely studying soilborne pathogens and root diseases in cereal crops. Because soilborne diseases like Rhizoctonia and Pythium grow rapidly, they can quickly infect germinating seeds and attack young seedlings. These fungal pathogens have the ability to prevent seedlings from ever breaking ground. Paulitz says in most crops, one of the major symptoms of these diseases is damping-off – the seed simply rots and never germinates. If crops do in fact get the chance to emerge, they will likely be stunted and patchy as the diseases continuously nibble away at the root tissue throughout the season.
Luckily, Fusarium, Pythium and Rhizoctonia have different life cycles and thrive under differing weather conditions, so their opportunity to increase levels of destruction in unison is fairly limited. Nevertheless, each pathogen has the ability to cause severe damage individually.
- “Fusarium infects the roots and eventually gets into the crown, or the bottom part of the stem near the soil. It manifests its symptoms later on in the growing season. This disease seems to be predisposed by drought stress.
- “Pythium infects germinating seeds and young seedlings very quickly and nibbles away at root tips. The disease is more prevalent in areas that have higher precipitation – more than 18-20 inches of precipitation annually and is favored by wet, poorly drained soils.
- “Rhizoctonia, similar to Pythium, infects roots and young seedlings early in the growing season. The disease is favored by wet, cool conditions, although the strains that cause bare patch symptoms are more common in soils that have more of a sandy or silty texture and receive less than 15 inches of precipitation a year," Paulitz and Schroeder explained.
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