Browse on keywords: disease rotation
Search results on 05/21/13
1404. Cook, R.J.. 1990 Jan.. Rotation effects and plant disease.. presentation at STEEP Annual Review, Moscow, ID.
In monocrop wheat, the average fumigation response is 70%. It drops to about 20% in a 2-year rotation (W-P) and to about 7% in the 3 year rotation (W-B-P). There is a 3-way complex of major disease organisms in our dryland cropping - Take-all, Pythium, and Rhizoctonia. Rhizoc. and Take-all are more severe in the drier areas. Pythium is more of a problem in the more acid, higher clay soils. Peas and lentils are good hosts for Rhizoc., yet wheat after peas is healthier. There is less plant material residue to act as a host for Rhizoc. after peas compared to after wheat. At Lind, WA, take-all decline did not occur with no-till. Once take-all decline set in, then the incidence of Rhizoc. increased. With rotation, you often don't need the tillage to help control disease. There has been a debate whether these diseases come from the soil or from the straw. Recent experiments found that the soil hosted the organisms, but the residue in the soil was an important food source. There was no effect on crop growth when straw from a previous crop was fumigated. In another test, there was no benefit from a paired-row configuration, either with fumigation or with a good rotation. Uniform row spacing is best when there is a higher risk for disease.
1466. Coventry, D.R. and J.F. Kollmorgen. 1987. An association between lime application and the incidence of take-all disease in wheat.. Aust. J. Exp. Agric., 27:695-699.
The effects of lime, deep ripping and fertilizer treatments on the occurrence of take-all symptoms in wheat. Although liming the soil increased damage by Gaeumanomyces graminis var. tritici, and perhaps other pathogens, the overall grain yields were not reduced because of the countering effect of lime promoting yield. Lime also altered the composition of grasses in pasture plots, resulting in more brome grass and barley grass. The control of take-all by crop rotations and controlling grassy weeds in pasture could be a necessary adjunct to liming if maximum yield benifits are to be obtained. Liming severely acid soils benifits the host more than the pathogen, whereas in moderately acid soils the reverse was true. The traditional rotation is a long-term clover ley pasture (5-8 yrs) with a significant component of annual grasses that host G. graminis var. tritici, followed by 2-4 years of consecutive cereal crops. This system therefore favours a build-up of inoculum of the take-all fungus and liming may therefore increase grain yield losses.
1819. Elliott, L.F. (ed.). 1987. STEEP - Conservation concepts and accomplishments.. Washington State Univ. Publ., 662pp..
A compilation of 48 papers covering: tillage and plant maagement; erosion and runoff predictions; plant design; pest management; socio-economic; integrated systems; technology transfer for cropping systems; 22 technical notes. T: many
2597. Herrman, T. and M.V. Wiese. 1984. Foot rot control in winter wheat using tillage, rotation, variety, fungicide, and nitrogen variables.. ID Agr. Expt. Sta. CIS #737.
Worst infection with conventional tillage; Stephens a more resistant variety; 3 yr rotation had lowest level, also lower levels with peas versus lentils; fungicides increased yields 4-6 bu/ac; no effect of level of N fertilizer; evidence from other areas that green manure could reduce infection levels; late fall tillage reduces infection; reduced tillage intensifies other diseases such as Cephalosporium stripe and Fusarium root rot. T: disease incidence by tillage, variety, fungicide.
5114. Pesik, J.. 1976. The influence of various proportions of cereals in crop rotation. Rostlina Vyroba, 22(XLIX).
Experiments demonstrated that grain yield was affected mostly by the forecrop. Clovers and barley, after a fertilized root crop, provided good forecrops. Neither increased N-rates nor organic fertilizing alone could compensate for the negative effect of less favorable forecrops. In the years with the incidence of leaf-diseases, the strongest attack was observed at the highest N-rates. The interaction of higher N-rates with organic matter compensated for the effect of unfavourable forecrops and resulted in high yields.
5981. Rovira, A.D.. 1986. Influence of crop rotation and tillage on Rhizoctonia bare patch of wheat.. Phytopathology, 76(7):669-673.
Rhizoctonia bare patch was more severe in direct drilled wheat than in wheat sown into cultivated soil. The area of affected crop was consistently larger when wheat followed a mixed annual pasture of grasses and Medicago spp. than when wheat followed wheat, peas, or grass-free pasture of Medicago spp. All isolates of R. solani were pathogenic on wheat, barley, peas, Medicago spp., annual ryegrass, and barley grass.
6359. Smiley, R., D. Wilkins, W. Uddin, S. Ott, K. Rhinhart, and S. Case. 1989. Rhizoctonia root rot of wheat and barley.. OR Agr. Expt. Sta. Special Report 840, p. 68-79..
Rhizoctonia root rot is now considered the most severe root disease of barley in the PNW. It is more important than take-all and Pythium on wheat produced in drier areas (<16" precip.). Based on long-term plots at Pendleton, different management systems are unlikely to greatly influence the biological resistance of soils to Rhizoctonia. Rotational crops susceptible to Rhizoctonia include wheat, barley, peas, chickpeas, lentils, and rapeseed. The disease is less apparent on small grains after legumes than after cereals. Rhizoctonia damage is always highest on no-till systems, but yields may not suffer due to improved water relations under conservation tillage. Australian research indicates that applications of N and P fertilizers can reduce the disease. There appear to be detrimental herbicide interactions with Rhizoctonia, particularly Glean on high pH soils. Also, the use of glyphosate increased disease incidence, perhaps by signalling the pathogens to move from the dying plants to newly seeded ones. A delay of at least 2 weeks is suggested between chem kill and planting of a new crop.
7524. White, J.G.H.. undated. Grain legumes in sustainable cropping systems; a review.. unpublished manuscript, Plant Science Dept..
This paper briefly reviews the role that grain legumes can play in sustaining cropping systems. It presents various estimates of N fixation of grain legumes, with lupin and fababean showing the highest rates, followed by peas and lentils, chickpeas, and soybeans. Phaseolus beans are generally poor N fixers. Fababeans are more tolerant of soil mineral N than other species and will still fix large quantities of N when mineral N is present. Under drought stressed conditions, peas and lentils were more efficient in N fixation than fababeans. Only in lupins and fababeans was N fixation normally greater than the N removed in the seed. The roots and nodules of grain legumes are likely to be the greatest source of N for following crops. This N is often quickly mineralized within several weeks after harvest, and strategies are needed to prevent its loss. Grain legumes are also beneficial break crops, particularly for soil-borne diseases, and can help to control certain grassy weeds. Preceding grain legumes with a brassica crop has reduced the incidence of Aphanomyces root rot in peas, due to sulfur containing compounds. Most grain legumes suffer reduced yields if soils are compacted and poorly aerated. The paper contains numerous references and tables on nitrogen relations.
8323. Cook, R.J.. 1990. presentation at Palouse Cons. Farm field day. .
A new combination of cropping practices appears to solve some disease problems in continuous wheat culture. Wheat straw is not toxic to wheat plants, but keeps the soil moist and favors disease. Cook suggested the following system: no-till, paired row, fertilizer placed beneath each row. The fertilizer shank disturbs the soil and inhibits certain disease organisms. Each plant has easy access to fertilizer beneath, and the P helps the seedling grow out of disease injury that may occur. P also stimulates root growth. The paired row opens up the canopy to some drying, which stops take-all and Rhizoctonia. This system is working in continuous no-till winter wheat in Pullman, and is also working in continuous no-till spring barley at Lind, WA. Cook suggested its use in the intermediate rainfall area. The fertilizer is placed at 5" depth and the seed at 1.5".
8384. Beus, C., D. Dillman, and J. Carlson. 1990. Palouse agriculture: a survey on production practices, policies, and problems.. unpublished results, Dept. of Rural Sociology, Washington St. Univ., Pullman, WA 99164.
This random survey was done in the Palouse area of eastern WA and northern ID, with a random sample of about 260 farmers. Average farm size was 1392 acres. One-third of the respondents would like to change their current rotation, primarily to reduce disease problems, but consider government programs to be the biggest barrier. Desire to use no-till planting was evenly split. Half the respondents felt they were using most of the available erosion control practices. Large percentages (>60%) felt that contour tillage, surface roughness, no-till, good plant cover, and tilth were very important erosion control factors. Herbicide and fertilizer use trends over the past five years were normally distributed. Use of fungicides on wheat (other than seed treatment) was generally less than 20%. Half the farmers currently use soil testing, and of those, 90% tested for residual N to 4-5 ft. depth. Half the respondents felt they had cut back on pesticide and fertilizer use since their high point, while only 10-20% felt they would do so in the future. About 65% had heard of the LISA program, and 26% indicated opposition to it.