Influence of Semiarid Cropping Systems on Root Diseases and Inoculum Density of Soilborne Pathogens

Abstract

Smiley, R. W., Machado, S., Gouriie, J. A., Pritchett, L. C, Yan, G. P, and Jacobsen, E. E. 2013. Infiuence of semiarid cropping systems on root diseases and inoculum density of soilbome pathogens. Plant Dis. 97:547-555.There is interest in converting the 2-year rotation of rainfed winter wheat with cultivated fallow in the Pacific Northwest of the United States into direct-seed (no-till) systems that include chemical fallow, spring cereals, and food-legume and brassica crops. Eight cropping systems in a low-precipitation region (<330 mm) were compared over 9 years to determine effects of changes on diseases. Fusarium crown rot was more prevalent in wheat following cultivated than chemical fallow, and Rhizoctonia root rot was more severe when winter wheat was rotated with chemical fallow than with no-till winter pea. Take-all occurred even during the driest years and was more severe on annual spring wheat than on annual spring barley. Inoculum density (picograms of DNA per gram of soil) differed (a < 0.05) among cropping systems for Fusarium culmorum, F pseudograminearum, Gaeumannomyces graminis var. tritici, and Pythium spp. but not for Rhizoctonia soiani AG-8. Phoma medicaginis var. pinodeila was detected only where winter pea was planted frequently. This is the first report of P. medicaginis as a component of the dryland stem rot complex of pea in north-central Oregon. Results of this investigation will provide guidance for developing crop species with resistance to Fusarium crown rot and black stem of pea.

Impact of agricultural practices and environmental variables on plant-parasitic nematode communities in fields at a landscape scale

“…It had already been demonstrated that tillage has a strong impact on the soil food web (Hendrix et al, 1986;Zhong et al, 2016) which could affect some of the PPN taxa by modifying the availability of weed roots. Here we highlighted the negative impact on Pratylenchus and Macrotrophurus, in line with the findings of Smiley et al (2013). In contrast with superficial tillage, tillage modifies the soil more deeply (Altieri, 1999;Franzluebbers, 2002), which could have a significant impact on their abundance (Rahman et al, 2007).…”

EFFECT OF SEED DRESSING CHEMICALS ON EMERGENCE, YIELD AND AGAINST SOIL & SEED BORN DISEASES OF WHEAT

“…Black point disease caused by Bipolaris sorokiniana and Alternaria alternata, is an important seed-borne disease in many wheat growing countries of the world ( Zishan et al, 2005;Hasabnis et al, 2006). Smiley et al, (2013) depicted that Fusarium spp. cause crown rot and often invade the emerging coleoptile and also reported that mostly wheat diseases are caused by fungi which attack seed, roots and foliage.…”

Aetiology and toxigenicity of Fusarium graminearum and F. pseudograminearum causing crown rot and head blight in Australia under natural and artificial infection

“…FCR is a chronic disease in most cereal producing regions and its prevalence and severity becomes pronounced under dryland conditions. It is of key economic significance to Australia, costing over A$80 million annually (Murray & Brennan, ), North America (Smiley et al ., ), South Africa (Lamprecht et al ., ) and west Asia and north Africa. FCR is predominantly caused by FP and F. culmorum , but others including F. acuminatum , F. avenaceum , F. crookwellense , F. equiseti and FG may also be involved (Akinsanmi et al ., ; Hogg et al ., ).…”