Management strategies to reduce losses caused by rhizoctonia seedling blight of field pea

2007 ◽  
Vol 87 (1) ◽  
pp. 145-155 ◽  
Author(s):  
S. F. Hwang ◽  
B. D. Gossen ◽  
R. L. Conner ◽  
K. F. Chang ◽  
G. D. Turnbull ◽  
...  

Seedling blight can cause substantial reductions in stand density of field pea on the Canadian prairies. Ninety-four isolates of Rhizoctonia solani were obtained from soil samples collected from 37 pea fields in 1999 in Alberta, Canada. Sixty isolates were characterized as anastomosis group (AG)-4 and 12 isolates as AG-2-1. Some of these isolates caused severe pre-emergence damping-off and were classified as highly pathogenic; 41 of the 44 highly pathogenic isolates were AG-4 and three were AG-2-1. Two highly pathogenic AG-4 isolates were used to assess the effect of inoculum density on survival and growth of field pea seedlings, and the impact of seeding date, seeding depth, soil temperature, seed damage, seed treatments and seeding density on seedling blight and root rot injury. As inoculum density increased, so did root rot severity, while seedling establishment, shoot dry weight and root dry weight declined. Under controlled conditions, seedling establishment in the noninoculated control increased as soil temperatures increased, but establishment and growth declined in inoculated treatments. In a temperature gradient study, seedling infection was highest when mean daily temperatures were 17.5°C or higher. In field trials over 8 station years, delayed seeding often resulted in reduced seedling establishment in inoculated treatments, although this trend was not consistent across sites or years. Seed yield consistently declined with later seeding dates. Seed treatment with fungicides (carbathiin + thiram, metalaxyl) improved establishment and productivity in inoculated treatments, especially where seed was damaged prior to planting. Seeding depth had no impact on root rot severity. Emergence and seed yield increased with seeding density, but increasing density beyond 90 seeds m-2 did not result in proportionately higher yields. These results indicate that a combination of seed treatment and early seeding can reduce Rhizoctonia injury to pea seedlings under field conditions. Key words: Pisum sativum, Rhizoctonia solani (AG-4), management, seeding depth, seeding rate

2014 ◽  
Vol 94 (2) ◽  
pp. 311-321 ◽  
Author(s):  
S. F. Hwang ◽  
H. U. Ahmed ◽  
G. D. Turnbull ◽  
B. D. Gossen ◽  
S. E. Strelkov

Hwang, S. F., Ahmed, H. U., Turnbull, G. D., Gossen, B. D. and Strelkov, S. E. 2014. The effect of seed size, seed treatment, seeding date and depth on Rhizoctonia seedling blight of canola. Can. J. Plant Sci. 94: 311–321. Rhizoctonia solani can have a substantial impact on seedling establishment and productivity of canola (Brassica napus). The effects of seeding date, seeding depth, seed size, and seed treatment on seedling blight of canola were evaluated under greenhouse and field conditions. Early seeding resulted in higher seedling emergence in one trial year and higher seed yield in all trial years relative to a late-seeded treatment. Mid-sized seed (range 0.7–2.0 mm diam.) had greater seedling emergence in R. solani-inoculated growth medium in a greenhouse trial and higher seed yield in one of two field trials compared with smaller seed (<0.7 mm). In the greenhouse study, sowing of large seed resulted in greater plant height and shoot weight compared with sowing of smaller seed. The effect of seeding depth was significant only on shoot dry weight, which increased at a seeding depth of 2.6 cm. Seed treatment with Helix Xtra (thiamethoxam+difenconazole+metalaxyl+fludioxonil), and Prosper FX (clothianidin+carboxin+trifloxystrobin+metalaxyl) resulted in a significant increase in seedling emergence and yield compared with the inoculated control. These results indicate that fungicidal seed treatment can minimize the impact of R. solani on canola.


2003 ◽  
Vol 83 (4) ◽  
pp. 959-967 ◽  
Author(s):  
S. F. Hwang ◽  
B. D. Gossen ◽  
K. F. Chang ◽  
G. D. Turnbull ◽  
R. J. Howard ◽  
...  

Studies were undertaken to assess the impact of seedling blight and root rot caused by Rhizoctonia solani AG-4 on nodulation and seed yield of chickpea. The effects of pathogen inoculum concentration and seed damage on disease severity were also measured. Chickpea seedlings were grown under controlled-environment conditions in sterilized soil amended with pathogenic isolates of R. solani and in field plot experiments where the inoculum was incorporated with the seed at planting. In greenhouse experiments, emergence and dry matter production declined and root rot severity increased with increasing inoculum concentration. Root rot reduced nodulation where lesions covered more than 25% of the root surface. For chickpea cultivar Sanford this level of infection was sufficient to reduce root mass, but for the cultivar Tyson, more than half of the root was covered with lesions before root mass began to decline. In a comparison of seed treatment fungicides, thiram + carbathiin (Vitaflo 280) and carbathiin + thiabendazole (Crown at 6 mL of product kg-1 seed) significantly increased seedling emergence and seed yield compared to the inoculated control. In an assessment of the effects of seed damage, seedling survival and seed yield were similar for both healthy and mechanically damaged seed. Rhizoctonia solani has the potential to be an important constraint to chickpea production in the prairie region of western Canada. Key words: Rhizoctonia solani, Cicer arietinum, seed treatment, fungicide, seeding date


2014 ◽  
Vol 94 (4) ◽  
pp. 693-700 ◽  
Author(s):  
K. F. Chang ◽  
R. L. Conner ◽  
S. F. Hwang ◽  
H. U. Ahmed ◽  
D. L. McLaren ◽  
...  

Chang, K. F., Conner, R. L., Hwang, S. F., Ahmed, H. U., McLaren, D. L., Gossen, B. D. and Turnbull, G. D. 2014. Effects of seed treatments and inoculum density of Fusarium avenaceum and Rhizoctonia solani on seedling blight and root rot of faba bean. Can. J. Plant Sci. 94: 693–700. Production of faba bean cultivars with tannin-free seed on the Canadian prairies has potential for use in human food and as a feedstock for livestock and aquaculture. However, root rot is a major constraint to production. The effects of fungicide seed treatments on root rot caused by Fusarium avenaceum and Rhizoctonia solani, and the effect of inoculum density on seedling emergence, nodulation, root rot severity and yield of faba bean were examined across 12 station years from 2009 to 2011 at sites in Manitoba and Alberta. Fusarium avenaceum reduced seedling emergence more than R.solani, but both pathogens had a similar impact on seed yield. The effects of inoculum density and seed treatment were generally significant for seedling emergence, root rot severity and seed yield for both pathogens. The interaction effects of inoculum density×seed treatment for F.avenaceum and R.solani were only significant for seed yield and seedling emergence. Seedling emergence and seed yield declined with increasing inoculum level for both F. avenaceum and R.solani. Fungicidal seed treatments with Apron Maxx (fludioxonil+metalaxyl) and Vitaflo 280 (carbathiin+thiram) consistently improved emergence and seed yield in trials inoculated with F.avenaceum or R.solani. This study demonstrated that seed treatment to manage root rot of faba bean is warranted.


2013 ◽  
Vol 93 (4) ◽  
pp. 619-625 ◽  
Author(s):  
K. F. Chang ◽  
S. F. Hwang ◽  
H. U. Ahmed ◽  
B. D. Gossen ◽  
G. D. Turnbull ◽  
...  

Chang, K. F., Hwang, S. F., Ahmed, H. U., Gossen, B. D., Turnbull, G. D. and Strelkov, S. E. 2013. Management strategies to reduce losses caused by fusarium seedling blight of field pea. Can. J. Plant Sci. 93: 619–625. Fusarium seedling blight can cause substantial reductions in the stand density of field pea in western Canada. In greenhouse experiments, emergence decreased and root rot severity rose with increasing inoculum density. In field trials in 2007 and 2008 near Edmonton, AB, seeding at different depths and seeding dates did not consistently affect emergence or yield in Fusarium-infested soils. In field experiments, emergence declined significantly with each increase in inoculum level. Also, seed yield were reduced at high levels of disease pressure. Treatment of seed with Apron Maxx improved emergence, nodulation and yield of treatments challenged with inoculum of F. avenaceum in both greenhouse and field experiments. This research demonstrates the need to prevent seedling blight and root rot through proper seed treatment.


2001 ◽  
Vol 81 (3) ◽  
pp. 509-517 ◽  
Author(s):  
S. F. Hwang ◽  
B. D. Gossen ◽  
K. F. Chang ◽  
G. D. Turnbull ◽  
R. J. Howard

When cool, wet conditions persist after planting, Pythium spp. can be an important constraint to stand establishment in field pea. Laboratory studies and field trials were conducted over 3 yr to assess the impact and evaluate the interactions of Pythium spp., metalaxyl seed treatment and damage to seed on seedling establishment, root rot severity and seed yield of field pea. Seedling emergence, seedling size, and seed yield were reduced by inoculation with Pythium spp. and by mechanical damage to the seed. Fungicide seed treatment reduced the impact of seed damage, but did not always restore seedling emergence and seed yield to the same level as from undamaged seed. Undamaged seed treated with metalaxyl was not affected by inoculation with Pythium spp. Differences among cultivars, although often significant, were small relative to the effect of seed injury. Laboratory studies showed a negative linear relationship between inoculum concentration and emergence from untreated seed. They also showed that Pythium spp. had a similar impact on seedling emergence in cool (20/10°C day/night) and cold (12/6°C) soils. This study showed that planting fungicide-treated, high-quality field seed was an effective means of maximizing emergence and stand establishment for commercial field pea production. Key words: Pisum sativum, seed vigour, metalaxyl, Pythium, seed damage


2015 ◽  
Vol 95 (2) ◽  
pp. 293-301 ◽  
Author(s):  
S. F. Hwang ◽  
H. U. Ahmed ◽  
G. D. Turnbull ◽  
B. D. Gossen ◽  
S. E. Strelkov

Hwang, S. F., Ahmed, H. U., Turnbull, G. D., Gossen, B. D. and Strelkov, S. E. 2015. Effect of seeding date and depth, seed size and fungicide treatment on Fusarium and Pythium seedling blight of canola. Can. J. Plant Sci. 95: 293–301. Seedling blight has a substantial impact on stand establishment and productivity of canola (Brassica napus) on the Canadian prairies. The effects of seeding date, seed size, seeding depth, and seed treatment fungicides on seedling blight of canola caused by Fusarium avenaceum and Pythium ultimum were evaluated under field conditions. In the trials inoculated with P. ultimum, early seeding reduced seedling emergence and seed yield in all 3 yr of the study. However, the interaction of F. avenaceum with seeding date was not consistent; inoculation with F. avenaceum reduced seedling emergence in early seeded canola in 1 of 4 yr, but emergence was higher in early than in mid-seeded treatments in 2 yr and there was no difference among seeding dates in 1 yr. Late seeding reduced seed yield in 2 of 4 yr in the F. avenaceum study. Seed size and seeding depth generally did not have an effect on seedling establishment or seed yield for either pathogen. Seed treatment with Helix Xtra (thiamethoxam+difenconazole+metalaxyl+fludioxonil) and Prosper FX (clothianidin+carboxin+trifloxystrobin+metalaxyl) fungicides increased seedling emergence and yield compared with the F. avenaceum-inoculated control. Seed treatment with Helix Xtra also increased seedling emergence and seed yield compared with the P. ultimum-inoculated control. Manipulation of seeding date did not substantially improve stand establishment or yield of canola when inoculum pressure was high. Seed treatment was the most effective strategy for reducing losses caused by seedling blight of canola in fields infested with F. avenaceum or P. ultimum.


2000 ◽  
Vol 22 (4) ◽  
pp. 392-399 ◽  
Author(s):  
S.F. Hwang ◽  
B.D. Gossen ◽  
G.D. Turnbull ◽  
K.F. Chang ◽  
R.J. Howard ◽  
...  

2003 ◽  
Vol 93 (3) ◽  
pp. 329-335 ◽  
Author(s):  
Allen G. Xue

Pea root rot complex (PRRC), caused by Alternaria alternata, Aphanomyces euteiches, Fusarium oxysporum f. sp. pisi, F. solani f. sp. pisi, Mycosphaerella pinodes, Pythium spp., Rhizoctonia solani, and Sclerotinia sclerotiorum, is a major yield-limiting factor for field pea production in Canada. A strain of Clonostachys rosea (syn. Gliocladium roseum), ACM941 (ATCC 74447), was identified as a mycoparasite against these pathogens. When grown near the pathogen, ACM941 often was stimulated to produce lateral branches that grew directly toward the pathogen mycelium, typically entwining around the pathogen mycelium. When applied to the seed, ACM941 propagated in the rhizosphere and colonized the seed coat, hypocotyl, and roots as the plant developed and grew. ACM941 significantly reduced the recovery of all fungal pathogens from infected seed, increased in vitro seed germination by 44% and seedling emergence by 22%, and reduced root rot severity by 76%. The effects were similar to those of thiram fungicide, which increased germination and emergence by 33 and 29%, respectively, and reduced root rot severity by 65%. When soil was inoculated with selected PRRC pathogens in a controlled environment, seed treatment with ACM941 significantly increased emergence by 26, 38, 28, 13, and 21% for F. oxysporum f. sp. pisi, F. solani f. sp. pisi, M. pinodes, R. solani, and S. sclerotiorum, respectively. Under field conditions from 1995 to 1997, ACM941 increased emergence by 17, 23, 22, 13, and 18% and yield by 15, 6, 28, 6, and 19% for the five respective pathogens. The seed treatment effects of ACM941 on these PRRC pathogens were greater or statistically equivalent to those achieved with thiram. Results of this study suggest that ACM941 is an effective bioagent in controlling PRRC and is an alternative to existing chemical products.


1991 ◽  
Vol 71 (4) ◽  
pp. 1271-1274 ◽  
Author(s):  
V. A. Fritz ◽  
C. J. Rosen

A 3-yr field experiment determined the influence of nitrogen (N) rates (0, 23, 46 and 92 kg ha−1), rhizobial inoculation, and fungicide (captan and thiram) seed treatment on the productivity of processing peas (Pisum sativum L.). In 2 of the 3 yr, N rates up to 46 or 92 kg N ha−1 increased vine fresh weight, decreased nodulation and had no effect on seed yield. Seeds treated with fungicides or inoculated with Rhizobium leguminosarum biovar viceae had no effect on vine fresh weight or seed yield. Nodule dry weight was increased in 2 of 3 yr when seeds were inoculated with Rhizobium. Key words: Pisum sativum, nodulation, rhizobia, fungicides


Plant Disease ◽  
1997 ◽  
Vol 81 (2) ◽  
pp. 175-179 ◽  
Author(s):  
Lindsey J. du Toit ◽  
H. Walker Kirby ◽  
Wayne L. Pedersen

A noncirculating aeroponics system was evaluated as a method for rapid screening of maize genotypes for resistance to Fusarium graminearum seedling blight/root rot. The system allows for nondestructive, repetitive sampling of seedlings for assessing disease progress and seedling growth. Shoot growth and root rot were assessed at 3-day intervals, and final shoot and root dry weight were determined 15 days after inoculation. The nine hybrids screened differed in severity of root rot as early as 6 days after inoculation, indicating differences in resistance to F. graminearum. Inoculation did not always significantly affect shoot growth, root dry weight, or shoot dry weight, but differences in these agronomic traits were observed among hybrids.LH119 × LH51 and Pioneer Brand 3379 showed the greatest resistance to root rot. Area under-disease progress curve and a critical stage of disease assessment (9 days after inoculation) gave similar rankings of hybrids for root rot resistance, indicating that a single disease assessment (versus multiple assessments) may be adequate in screening for resistance with this aeroponics system.


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