Diseases Caused by Root-Infecting Pathogens in Dryland Agriculture

Cook, Robert

doi:10.1007/978-1-4613-8982-8_11

Cited by 29 publications

(9 citation statements)

References 63 publications

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“…Little research has been conducted on the mechanism(s) of the break-crop effect. A common hypothesis for the effect is that Ggt is weakened when denied access to host roots (Cook, 1990).…”

Section: Introductionmentioning

confidence: 99%

Biofumigation: Isothiocyanates released frombrassica roots inhibit growth of the take-all fungus

et al. 1994

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The presence of root tissue of the brassicas canola and Indian mustard inhibited growth of pure cultures of the fungal pathogen which causes take-all of wheat [Gaeumannomyces graminis (Sacc.) Arx and Oliver var. tritici, abbreviated as Ggt]. Ggt growth was generally inhibited more in the presence of Indian mustard roots than canola roots. Dried irradiated roots were consistently effective in reducing Ggt growth, but growth inhibition by young live roots and macerated roots was not consistent. The inhibitory compound(s) were shown to be volatile because the symmetry of Ggt growth was not affected by the proximity of the Brassica tissue. Volatile breakdown products from macerated Brassica roots were identified using a gas chromatograph-mass spectrometer. The major compounds found were isothiocyanates (ITCs). Canola roots released mostly methyl ITC and Indian mustard roots released mostly phenylethyl ITC. Low concentrations of these and related compounds inhibited growth of Ggt in pure culture when supplied as the vapour of pure chemicals in concentrations within the range expected during breakdown of Brassica roots in soil.

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“…Little research has been conducted on the mechanism(s) of the break-crop effect. A common hypothesis for the effect is that Ggt is weakened when denied access to host roots (Cook, 1990).…”

Section: Introductionmentioning

confidence: 99%

Biofumigation: Isothiocyanates released frombrassica roots inhibit growth of the take-all fungus

et al. 1994

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“…About half of the annually cropped area (annual precipitation >400–450 mm) is planted every third or fourth year to a cool‐season pulse crop, canola ( Brassia napus L. or B. rapa L.), but even these rotations include wheat or barley 2 in every 3 or 3 in every 4 yr. Results with soil fumigation used as a research tool showed that the average yield response to fumigation was 70, 22, and 7%, respectively, for winter wheat grown in the same field every year, every other year, or every third year (Cook, 1990; Cook and Veseth, 1991). The drier parts of the region are managed in a winter wheat–fallow or winter wheat, spring cereal, fallow rotation, but the trend is away from fallow because of its contribution to erosion (Papendick, 1998) and because of the inefficiency of producing only one crop every 2 yr.…”

mentioning

confidence: 99%

Influence of Paired‐Row Spacing and Fertilizer Placement on Yield and Root Diseases of Direct‐Seeded Wheat

et al. 2000

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Root diseases, namely take‐all caused by Gaeumannomyces graminis (Sacc.) Arx & D. Olivier var. tritici J. Walker, Rhizoctonia root rot caused by R. solani Kühn AG8, and Pythium root rot caused by several Pythium Pringsh. species, become yield‐limiting to wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) in the Inland Pacific Northwest when these crops are grown without adequate rotation, especially in direct‐seed (no‐till) systems. We tested whether yields of wheat could be increased by (i) pairing the rows rather than spacing them uniformly, so as to keep the crop canopy open longer into the growing season, and (ii) placing fertilizer within rather than between the rows, so as to make nutrients more accessible to diseased roots. All experiments were done in fields with a recent history of intensive wheat. Direct seeding was used to further intensify pressure from root diseases, and soil fumigation and/or stubble burning were used in some experiments to reduce pressure from root diseases. Mixed effect models were used to analyze the yield results, with location (observation) treated as the random effect. When all yield data for four winter wheat experiments were used, and spacing, fumigation, and their interaction were the fixed effects in the model, spacing and fumigation but not their interaction were significant. When the yield data were limited to fertilizer placed within each row (directly beneath the seed), spacing, fumigation, and their interaction all were significant. However, when the yield data were limited to fertilizer placed between the rows, or to yields from plots without straw on the soil surface, neither spacing, fumigation, nor their interaction were significant. Similar results were obtained in a spring wheat experiment where fumigation, row spacing, and fertilizer placement were tested in all combinations. Moreover, the amount of Rhizoctonia root rot, take‐all, or both were less in response to paired‐row spacing in two winter wheat experiments. The higher yields can be explained by the microenvironmental benefits of a more open canopy with paired rows together with the concentration of soil disturbance and row cleaning with paired shanks (presumably resulting in more warming and drying of the top soil where the pathogens are most active), and placement of fertilizer directly beneath each seed row, all of which have the potential to reduce the effects of root diseases.

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“…However, yield advantages from crop rotation are commonly observed even at high levels of fertilizer application (Heichel and Barnes, 1984;Voss and Schrader, 1984). Non-N benefits of crop rotation have been attributed to improvements in soil microbiological and biochemical conditions and reductions in pathogen populations (Cook, 1990;Bullock, 1992;Karlen et al, 1994). Rotation benefits can be particularly marked under stressful growing conditions, including years with cool spring temperatures and mid-summer droughts (Porter et a!., 1997b ).…”

Section: Longer Crop Rotationsmentioning

confidence: 99%

“…This type of reduction in crop diversity across the landscape is related to low diversity in individual fields over time. More than 90% of the >21 million acres planted with corn and soybean in Iowa in 1991 contained only those two crops in 1989and 1990(USDA-ERS, 1992. Intensification of crop production in Iowa through drainage and field enlargement has resulted in a reduction of wetland vegetation and tree cover along streams and former field borders (Schultz et a!., 1997).…”

Section: Introductionmentioning

confidence: 99%

Diversity: A Key Element of Sustainable Agricultural Systems

Liebman

1998

Proceedings of the Integrated Crop Management Conference

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Diseases Caused by Root-Infecting Pathogens in Dryland Agriculture

Cited by 29 publications

References 63 publications

Biofumigation: Isothiocyanates released frombrassica roots inhibit growth of the take-all fungus

Biofumigation: Isothiocyanates released frombrassica roots inhibit growth of the take-all fungus

Influence of Paired‐Row Spacing and Fertilizer Placement on Yield and Root Diseases of Direct‐Seeded Wheat

Diversity: A Key Element of Sustainable Agricultural Systems

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