Effects of cultivation on Rhizoctonia root rot, cereal cyst nematode, common root rot and yield of wheat in the Victorian Mallee

1991 ◽  
Vol 31 (3) ◽  
pp. 367 ◽  
Author(s):  
RFde Boer ◽  
JF Kollmorgen ◽  
BJ Macauley ◽  
PR Franz ◽  
Boer RF De

The effects of method, time and number of cultivations on root diseases and yield of wheat were studied in a field experiment, in 1985, on a calcareous sandy loam in the Victorian Mallee. The incidence and severity of rhizoctonia root rot (Rhizoctonia solani) were higher in direct-drilled wheat than in wheat sown after cultivation. Compared with direct drilling, the severity of rhizoctonia root rot in seedlings was reduced by 40% with cultivation 20 weeks before sowing; by 70% with cultivation 1 day before sowing; and by 90% with 2 cultivations, the first at 16 weeks and the second 1 day before sowing. Cultivation generally increased the incidence of common root rot (Bipolaris sorokiniana) but had no significant effects on the severity of damage by the cereal cyst nematode (Heterodera avenae) or the number of nematode cysts produced, compared with direct drilling. The incidence and severity of root diseases, and the number of H. avenae cysts produced, were not significantly different in wheat sown after rotary hoeing than in wheat sown after scarifying. The severity of damage by H. avenae, the number of nematode cysts and the incidence of common root rot were higher (45, 70 and 36%, respectively) when scarifying was done 1 day before sowing, compared with scarifying 20 weeks earlier. Differences in sowing depth probably caused this effect since seed was sown deeper (as indicated by subcrown internode lengths) and plant emergence was less in the latter treatment. The timing and number of cultivations with a rotary hoe, however, did not significantly affect the severity of damage by H. avenae, the number of nematode cysts or the incidence of common root rot. The incidence of common root rot was correlated (r = 0.71) with the subcrown internode lengths, indicating that the deeper the seed was sown the greater the proportion of plants with the disease. Dry weight of seedlings and grain yield were negatively correlated (r = -0.79 and -0.66) with the severity of damage caused by H. avenae. Plant dry weight and grain yield were, however, not correlated with the severity of rhizoctonia root rot or the incidence of common root rot.

1976 ◽  
Vol 54 (14) ◽  
pp. 1656-1665 ◽  
Author(s):  
P. R. Verma ◽  
R. A. A. Morrall ◽  
R. D. Tinline

The effects of common root rot (Cochliobolus sativus) on plant biomass and grain yield in naturally infected Triticum aestivum cultivar Manitou were studied at Matador, Saskatchewan, by sampling plants at intervals from seeding to maturity in 1969, 1970, and 1971. Plants were categorized according to the extent of subcrown internode lesions as clean, slight, moderate, or severe. Dry weights and grain yields of plants in each category were determined. Decreasing mean dry weight per plant at all dates and grain yield per plant were consistently associated with increasing disease severity. Significant differences in biomass and grain yield generally existed between clean and slight, slight and severe, and moderate and severe categories. Very close relationships existed between losses in biomass and grain yield both per plant and per unit area. Overall mean biomass losses at maturity in severe, moderate, and slight plants as compared with clean were 58%, 37%, and 25%, respectively; losses in grain yield were 59%, 38%, and 26%, respectively. Biomass losses per square metre increased steadily with time, in all treatments. Grain yield losses per square metre for 1969, 1970, and 1971 summer-fallow checks were 30, 35, and 30%, respectively; the biomass losses at the final sampling dates were analogous.


1996 ◽  
Vol 36 (6) ◽  
pp. 683 ◽  
Author(s):  
DK Roget ◽  
SM Neate ◽  
AD Rovira

Effect of tillage treatments on the cereal root diseases, rhizoctonia root rot, take-all and cereal cyst nematode, and on grain yield of cereals were tested in 4 field experiments over 3 years. Conventionally cultivated treatments were compared with a range of direct-drill treatments using either a standard tined seed drill equipped with 10 cm sowing points, a specialised drill designed to give minimal soil disturbance or a standard tined seed drill equipped with a range of commercial or modified narrow points designed to provide soil disturbance from 0 to 5.0 cm below seed depth. Direct-drilled treatments that disturbed the soil below seed depth (DDD) and treatments that included 1 cultivation prior to sowing (CPS) resulted in a reduction of rhizoctonia root rot when compared with direct-drilled treatments that did not disturb the soil below seed depth (DDN). When seasonal conditions encouraged volunteer plant growth before sowing, a chemical fallow treatment applied 3 weeks before sowing significantly reduced rhizoctonia root rot in all direct-drilled plots. This was a significant factor in DDD treatments providing effective control of rhizoctonia root rot. Take-all was present in 3 of the 4 experiments. In 2 experiments, take-all was significantly higher in plots following DDN treatments than DDD or CPS treatments and in 1 experiment there was no effect of tillage. Cereal cyst nematode was present in 1 of the 4 experiments. The level of root damage from cereal cyst nematode was least in plots following DDN treatments, higher following DDD treatments and highest following CPS treatments. The influence of tillage practice on grain yield was closely related to the effect of tillage on cereal root disease when levels of disease were moderate to high. Where the incidence of root disease was low, grain yield differences due to tillage treatments were generally related to agronomic factors such as seed depth and seedbed condition.


1976 ◽  
Vol 54 (24) ◽  
pp. 2888-2892 ◽  
Author(s):  
P. R. Verma ◽  
R. A. A. Morrall ◽  
R. D. Tinline

The effects of common root rot (Cochliobolus sativus) on components of grain yield in naturally infected Triticum aestivum cultivar Manitou were studied at Matador, Saskatchewan, by sampling plants at maturity in 1969, 1970, and 1971. Plants were sorted into severe (SE), moderate (MO), slight (SL), and clean (CL) categories based mainly on the extent of lesions on the subcrown internodes. The number of tillers per plant, the number and weight of grains per head, the weight per head, and the 1000-kernel weight in each category were determined. Increasing values of all five components were consistently associated with decreasing disease severity. SE was mostly significantly different from the other three categories in all components except 1000-kernel weight; differences between SL and MO were usually non-significant. CL and SL were mostly significantly different for the number of tillers per plant and weight per head but non-significant for the weight and number of grains per head and 1000-kernel weight. Apparently, the major effect of common root rot was to reduce the number of tillers per plant and number of grains per head.


2019 ◽  
Vol 12 (2) ◽  
pp. 91-96
Author(s):  
M.I.E. Arabi ◽  
E. Al-Shehadah ◽  
M. Jawhar

Abstract The yield response of widely grown cultivars and landraces of Syrian wheat challenged with common root rot (CRR: Cochliobolus sativus) was measured by comparing plots with and without artificial inoculation under experimental conditions in two consecutive seasons. The results showed that response to CRR differed depending on the susceptibility levels of the wheat cultivars, and that the disease significantly (P<0.05) reduced grain yield, number of tillers and kernel weight. The diseased plants had fewer tillers which consequently reduced grain yield per plant. Yield losses of Triticum durum cultivars were higher than those of Triticum aestivum. In addition, the T. durum landrace Horani exhibited the best level of resistance to the disease, which indicates that this landrace might be a candidate donor for resistance in future breeding programmes. As CRR can dramatically reduce wheat grain yields under favorable conditions, management practices that reduce disease severity are highly recommended.


1990 ◽  
Vol 41 (4) ◽  
pp. 619 ◽  
Author(s):  
JM Wilson ◽  
J Hamblin

The effects of soil fumigation (98% methyl bromide + 2% chloropicrin at 580 kg/ha) and N fertilizer (0, 12.5, 25, 50 or 100 kg N/ha) were examined in field trials on continuous wheat and wheat in rotation with lupins on the Geraldton sandplain. Fumigation increased grain yields at N fertilizer levels more or =25 kg/ha and was associated with reduced incidence and severity of common root rot (Bipolaris sorokiniana)[Cochliobolus sativus]. Grain yield was not significantly affected by rotation. Fumigation increased soil ammonium levels and decreased soil nitrate levels. Rotation of wheat and lupins increased mid-season growth at all levels of applied N but only increased grain yield where no N was applied.


1982 ◽  
Vol 62 (4) ◽  
pp. 885-891 ◽  
Author(s):  
L. J. DUCZEK ◽  
L. J. PIENING

The effects of variable seeding depth and dates of seeding of barley on the incidence of root rot, and on emergence and grain yield were investigated in field trials at Saskatoon and Scott, Saskatchewan. The effect of variable seeding depth of barley on intensity of root rot, grain yield, loss of yield due to root rot, and the effect of variable seed size of barley on incidence of root rot and yield were also investigated in field trials at Lacombe, Alberta. Symptoms of common root rot, based on lesions on the subcrown internode, were not influenced by seed size or seeding date but the disease increased with depth of seeding. Grain yield decreased with depth and with late seeding. Emergence was not affected by seeding date but decreased with depth of seeding. Common root rot was not associated with the reduced yields of later seeding dates but was associated with reduced yields of increased seeding depths. The increased emergence and reduced disease at shallow depths resulted in a greater number of clean plants which probably accounts for some of the increased grain yield at shallow seeding depths.


1993 ◽  
Vol 73 (4) ◽  
pp. 1177-1187 ◽  
Author(s):  
L. J. Duczek ◽  
G. B. Wildermuth

Field tests at Saskatoon, Saskatchewan, Canada indicated no evidence of tolerance to common root rot in four spring wheat cultivars. There was a relationship between increased yield losses and increasing disease. In barley, the relationship was inconsistent in four cultivars and there was evidence of tolerance or recovery in Melvin with the number of seeds per head increasing with the level of disease. In Queensland, Australia there was evidence of tolerance in the wheat cultivar Banks across two locations, but the response was not consistent in all cultivars. Dry matter loss at immature growth stages was not related to grain yield loss. The inconsistent expression of tolerance in wheat, the difficulty of assessing it, and the difficulty of distinguishing tolerance from recovery suggest that the assessment of tolerance is not a reliable method of determining the reaction to common root rot. The relationship between loss in dry matter and grain yield, as disease increased, indicates that disease assessment should continue to be based on severity of symptoms. The evidence of tolerance to common root rot in barley suggests research on tolerance should concentrate on barley instead of wheat. Key words: Cochliobolus sativus, common root rot, tolerance, wheat, barley


1992 ◽  
Vol 43 (1) ◽  
pp. 43 ◽  
Author(s):  
GB Wildermuth ◽  
RD Tinline ◽  
RB McNamara

The effects of common root rot (CRR) caused by Bipolaris sorokiniana on grain yield, number of tillers, number of grains and grain weight of wheat plants were determined in four field experiments. Sites with different soil populations of B. sorokiniana were selected and inoculum of the fungus added to some plots. Disease and yield measurements were made on eight cultivars and lines differing in susceptibility to CRR. Timgalen, Songlen and Hartog were susceptible whereas Kite, 1008 C16, 141-4 and ISWYN 32 were partially resistant to CRR. Grain yield, tiller and grain number, but not grain weight decreased as disease severity increased. Diseased plants had lower tiller numbers than healthy ones and as a consequence a reduced number of grains and grain yield per plant. Five methods were compared for estimating yield loss caused by the disease. Polynomial regression equations for each cultivar between yield and disease rating of sub-crown internodes or multiple regression equations between yield and disease parameters of sub-crown internodes or tiller bases were established. A third method involved the projection of yield losses from one cultivar to other cultivars and in a fourth method yield losses were estimated from actual yields. In addition, an equation Yield loss (%) = 3 46 + 0.23 disease severity) (%) was established in one experiment and used as a fifth method in the other experiments. Yield losses estimated by methods 1 and 2 were similar and higher than those from the other methods. In areas where disease severity is high, methods 1 and 5 appear to be the most suitable for determining yield losses. Losses in a susceptible cultivar, Timgalen, varied between 13.9 and 23.9% whereas those in a partially resistant cultivar, 1008 C16, varied between 6.8 and 13.6%.


1982 ◽  
Vol 22 (116) ◽  
pp. 201 ◽  
Author(s):  
A Simon ◽  
AD Rovira

A survey of 14 farmers' fields in the Northern Adelaide Plains in 1978 showed that cereal cyst nematode (Heterodera avenae Woll.) was the major factor limiting wheat yields, with a relation of r = -0.86 (P < 0.001) between damage to wheat roots at the seedling stage and grain yield. None of the 12 physical and chemical properties of the soils measured was related to cereal cyst nematode damage or grain yield. Samples taken from experimental plots with similar soil and climate showed a build up of H. avenae after four successive wheat crops and highly significant negative correlations between the damage to seminal roots by H. avenae, dry weight at flowering, and grain yield. A highly significant positive correlation of 0.84 existed between the damage to the seminal roots and the number of females (white cysts) on the roots at flowering.


1994 ◽  
Vol 74 (1) ◽  
pp. 1-6 ◽  
Author(s):  
C. A. Grant ◽  
L D. Bailey

Field studies were conducted on two soil types testing low in Clover a 4-yr period to assess the influence of K and Cl fertilization under zero (ZT) and conventional tillage (CT) management on common root rot, dry matter yield at heading, and grain yield of Heartland barley. Tillage did not influence incidence of common root rot in the 4 site-yr where assessments could be taken. Common root rot incidence was reduced by KCl applications in 1 out of 4 site-yr. Dry matter yield at heading and grain yields were consistently higher with ZT than with CT on the silty clay soil, but only in 1988 on the fine sandy loam soil. The higher yields with ZT than with CT may be due to greater moisture conservation under the ZT management system. Response to K or Cl applications was generally not influenced by tillage treatment. Applications of Cl had little influence on either dry matter yield at heading or grain yield, despite the low initial Cl levels in the soils. Application of fertilizers containing Cl, therefore, may not be consistently beneficial, even on soils testing low in Cl. Key words: Potassium, chloride, tillage, barley, common root rot


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