Chemical control of the seed-corn maggot,Hylemya platura (Meigen), and seed-piece decay in potato seed pieces

1971 ◽  
Vol 48 (10) ◽  
pp. 374-380 ◽  
Author(s):  
B. J. Landis ◽  
Jfrome A. Onsager ◽  
Lee Fox ◽  
L. L. Foiles

1961 ◽  
Vol 38 (11) ◽  
pp. 388-395 ◽  
Author(s):  
Roland F. Line ◽  
Carl J. Eide


Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 172-172 ◽  
Author(s):  
R. D. Peters ◽  
H. W. Platt ◽  
K. A. Drake ◽  
R. H. Coffin ◽  
S. Moorehead ◽  
...  

Potato (Solanum tuberosum L.) diseases incited by Fusarium spp. include postharvest dry rot and seed-piece decay. Fusarium seed-piece decay is commonly controlled by preplant applications of chemical seed treatments. However, isolates of Fusarium spp. resistant to benzimidazole fungicides have been reported (2,4). In the spring of 2007, samples of cut seed tubers (cvs. Shepody and Russet Burbank) showing extensive symptoms of decay were received from three seedlots in Prince Edward Island (PE) and one seedlot in Saskatchewan (SK), Canada. All seed tubers had been treated with fludioxonil (Maxim Potato Seed Protectant [PSP], 0.5% fludioxonil) following cutting and then stored for 10 to 14 days prior to planting. Using standard isolation protocols (4), the 19 potato tuber pieces examined from PE and 2 from SK yielded 21 Fusarium isolates for further study. Five isolates (including both isolates from SK) were identified as Fusarium sambucinum Fuckel and the remaining 16 isolates were identified as F. coeruleum (Libert) Sacc. (3). To confirm identifications, isolates were compared with two known standards of each of F. sambucinum and F. coeruleum identified by K. Seifert (Agriculture and Agri-Food Canada, Ottawa, ON) by DNA sequencing of the partial β-tubulin gene or the translation elongation factor 1-α ( http://fusarium.cbio.psu.edu ; [1]). These standard isolates were also used as fludioxonil-sensitive controls in amended agar assays for chemical sensitivity. Agar plugs (5 mm in diameter) taken from the margins of 7-day-old cultures of the Fusarium isolates were transferred to petri dishes containing ½-strength potato dextrose agar amended with 0, 0.1, 1.0, 10.0, or 100.0 mg/liter of fludioxonil. Fludioxonil (Maxim PSP, 0.5% a.i.) was prepared as a stock solution in sterile distilled water and added to the molten agar after autoclaving. Culture incubation and mycelial growth measurements were performed as described previously (4). Measurements from four replicate petri dishes per concentration of fludioxonil were taken. Calculated EC50 values (fludioxonil concentration inhibiting pathogen growth by 50%) were obtained. The trial was repeated three times. The two standard isolates of F. sambucinum were sensitive to fludioxonil, with mean EC50 values of 0.002 (±0.002 standard error [SE]) and 0.005 (±0.002 SE) mg/liter. The two standard isolates of F. coeruleum were also sensitive to fludioxonil, with mean EC50 values of 0.17 (±0.005 SE) and 0.19 (± 0.005 SE) mg/liter. All other tested isolates of F. sambucinum and F. coeruleum were resistant to fludioxonil and showed no growth inhibition even at 100 mg of fludioxonil per liter. To our knowledge, this is the first report of resistance to fludioxonil in isolates of Fusarium spp. causing potato seed-piece decay. Since the isolates of F. sambucinum were also resistant to thiophanate-methyl and thiabendazole (data not shown), multiclass (benzimidazole and pyrrole) resistance was also documented. References: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (2) L. M. Kawchuk et al. Am. Potato J. 71:185, 1994. (3) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, 1983. (4) R. D. Peters et al. Plant Dis. 85:1030, 2001.



1942 ◽  
Vol 19 (2) ◽  
pp. 19-23 ◽  
Author(s):  
O. H. Elmer


2020 ◽  
Author(s):  
Xiaoyu Zhang ◽  
Xing Xing ◽  
Yayan Feng ◽  
Zhuo Yu ◽  
Jianjun Hao ◽  
...  

Abstract Background: Rhizoctonia solani causes stem canker and significantly impacts the production of potato. Conventional assay to evaluate potato resistance using R. solani inoculum is time consuming. To establish an effective and fast assay, 20 potato germplasms were examined using both R. solani inoculum and R. solani-derived toxin (RS toxin). Results: In field trials of 2009 and 2010, wheat-bran-based inoculum of R. solani was incorporated at either 0, 2, 3, 4 or 5 g per seed piece in the soil followed by sowing potato seed pieces in the furrow. Stem canker was evaluated in the growing season. Inoculum of wheat-bran-based 2, 3, or 4 g could well distinguish resistance of potato germplasms. For a quick assay of resistance screening, a toxin-based method was established by treating potato seedlings with the toxin of R. solani (RS toxin). RS toxin was prepared by heating R. solani culture. Potato seedlings were obtained through tissue culture and grown in Murashige and Skoog medium. Seedlings at the stage of 12 cm in height were transferred into agar medium amended with RS toxin and incubated for eight days. The inhibition caused by RS toxin was positively correlated with toxin concentration. By evaluating various potato cultivars that have different sensitivities to toxin, the inhibition of potato stems sections and seedlings was from 33% to 100% and from 32% to 148%, respectively. Results of toxin-based evaluation were highly correlated with the field data using pathogen inoculum (r = 0.731, P < 0.01). Conclusions: Inoculation with wheat bran-mediated R. solani of 2, 3 or 4 g per seed piece was an effective method for the evaluation of potato resistance in field trials. The toxin-based assay could improve efficiency and speed of disease resistance evaluation of potato germplasms. Both assays showed that none of the 20 potato materials was completely resistant to R. solani. However, cultivar ‘Desiree’ had the lowest level of disease, whereas ‘Atlantic’, ‘Favorita’, and ‘Shepody’ showed the high susceptibility.



2002 ◽  
Vol 3 (1) ◽  
pp. 14 ◽  
Author(s):  
Mary L. Powelson ◽  
Robin Ludy ◽  
Heather Heather ◽  
Debra A. Inglis ◽  
Babette Gundersen ◽  
...  

Planting of potato seed pieces infected with Phytophthora infestans can lead to the introduction of late blight within a planting. When infected seed pieces are planted, there are three resulting scenarios: (i) a healthy plant emerges, (ii) no plant emerges because of the rapid decay of the seed piece, or (iii) a symptomatic plant emerges. A major factor favoring stand establishment and seed transmission is the severity of seed piece infection. When infection is severe, stand is compromised and transmission rate is low. When infection is mild, the plant emerges before the seed piece decays and, in some instances, the pathogen makes its way from the seed piece to the plant where a stem lesion is formed. Diseased seed tubers are the principle source of late blight inoculum for infection of healthy seed pieces. Treatment of infected or blighted seed tubers with a seed dressing with activity against P. infestans is not a viable tactic because the products are ineffective against established infections. Conversely, treatment of healthy seed pieces provides a high level of protection against late blight spores that are spread during the seed handling and planting operations. Optimum effectiveness is achieved when products are applied immediately following cutting, as none are effective against established infections. Seed treatment reduces the risk of seed transmission of late blight and enhances stand establishment and plant vigor. This tactic should be an important component of an integrated late blight management program. Accepted for publication 16 January 2002. Published 29 January 2002.



1972 ◽  
Vol 49 (1) ◽  
pp. 7-11 ◽  
Author(s):  
L. V. Busch ◽  
R. G. Rowberry


1954 ◽  
Vol 31 (9) ◽  
pp. 297-297
Author(s):  
John L. Nickel


1954 ◽  
Vol 31 (8) ◽  
pp. 245-251 ◽  
Author(s):  
John L. Nickel


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