2,3-Di-(E)-caffeoyl-(2R,3R)-(+)-tartaric acid in terminals of peanut (Arachis hypogaea) varieties with different resistances to late leaf spot disease (Cercosporidium personatum) and the insects tobacco thrips (Frankliniella fusca) and potato leafhopper (Empoasca fabae).

1994 ◽  
Vol 42 (7) ◽  
pp. 1572-1574 ◽  
Author(s):  
Maurice E. Snook ◽  
Robert E. Lynch ◽  
Albert K. Culbreath ◽  
Catherine E. Costello
Plant Disease ◽  
2021 ◽  
Author(s):  
Albert Culbreath ◽  
Robert Kemerait ◽  
Timothy Brenneman ◽  
Emily Cantonwine ◽  
Keith Rucker

In peanut (Arachis hypogaea) production, in-furrow applications of the pre-mix combination of the SDHI fungicide/nematicide, fluopyram, and the insecticide, imidacloprid are used primarily for management of nematode pests and for preventing feeding damage on foliage caused by tobacco thrips (Frankliniella fusca). Fluopyram is also active against many fungal pathogens. However, the effect of in-furrow applications of fluopyram on early leaf spot (Passalora arachidicola) or late leaf spot (Nothopassalora personata) has not been characterized. The purpose of this study was to determine the effects of in-furrow applications of fluopyram + imidacloprid or fluopyram alone on leaf spot epidemics. Field experiments were conducted in Tifton, GA in 2015, 2016, and 2018-2020. In all experiments in-furrow applications of fluopyram + imidacloprid provided extended suppression of early leaf spot and late leaf spot epidemics compared to the nontreated control. In 2020, there was no difference between the effects of fluopyram + imidacloprid and fluopyram alone on leaf spot epidemics. Results indicated that fluopyram could complement early season leaf spot management programs. Use of in-furrow applications of fluopyram should be considered as an SDHI fungicide application for resistance management purposes.


Author(s):  
K. Karunanithi ◽  
G. Senthilraja ◽  
K. Subrahmaniyan

Forty two groundnut (Arachis hypogaea) cultivars were screened for resistance to Phaeoisariopsispersonata under glasshouse conditions. Among them, two germplasms (VG19561 and VG19654) were found to have resistance against late leaf spot. Biochemical parameters such as, phenylalanine ammonia-lyase, peroxidase, polyphenol oxidase and total phenols were estimated among the resistant germplasms and susceptible check, VRI2. biochemical analysis revealed the increased activities of the enzymes viz., phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, and phenolics in the resistant germplasms viz., VG19561 and VG19654 than the susceptible check, VRI 2.


Author(s):  
Ye Chu ◽  
H. Thomas Stalker ◽  
Kathleen Marasigan ◽  
Chandler M. Levinson ◽  
Dongying Gao ◽  
...  

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 879-884 ◽  
Author(s):  
Shouan Zhang ◽  
M. S. Reddy ◽  
Nancy Kokalis-Burelle ◽  
Larry W. Wells ◽  
Stevan P. Nightengale ◽  
...  

A disease assay was optimized for late leaf spot disease of peanut using Cercosporidium per-sonatum in the greenhouse, and this assay was used in attempts to elicit induced systemic resistance using strains of plant growth-promoting rhizobacteria (PGPR) and chemical elicitors. Nineteen strains of spore-forming bacilli PGPR, including strains of Paenibacillus macerans, Brevibacillus brevis, Bacillus laterosporus, B. subtilis, B. pumilus, B. amyloliquefaciens, B. sphaericus, B. cereus, and B. pasteurii, which previously elicited systemic disease control activity on other crops, were evaluated in greenhouse assays. Seven PGPR strains elicited significant disease reduction in a single experiment; however, none repeated significant protection achieved in the greenhouse assay, while significant protection consistently occurred with the fungicide chlorothalonil (Bravo). In other greenhouse trials, neither stem injections of C. personatum nor foliar sprays of chemicals, including salicylic acid, sodium salicylate, isonicotinic acid, or benzo[1,2,3]thiadiazole-7-carbothioc acid S-methyl ester (Actigard), which elicit systemic acquired resistance on other crops, elicited significant disease protection. In contrast, foliar sprays with DL-β-amino-n-butyric acid (BABA), which is an elicitor of localized acquired resistance, resulted in significantly less late leaf spot disease in one of two tests. Combination treatments of four PGPR strains with BABA in the greenhouse did not significantly protect peanut from late leaf spot. Field trials conducted over two growing seasons indicated that none of the 19 PGPR strains, applied as seed treatments at two concentrations, significantly reduced late leaf spot disease. The same chemical elicitors tested in the greenhouse, including BABA, did not elicit significant disease protection. Some combinations of four PGPR and BABA significantly reduced the disease at one but not at two sample times. Collectively, these results suggest that late leaf spot resistance in peanut is not systemically inducible in the same manner as is resistance to diseases in other crops by PGPR and chemical inducers.


2012 ◽  
Vol 03 (05) ◽  
pp. 582-588 ◽  
Author(s):  
L. Tshilenge-Lukanda ◽  
K. K. C. Nkongolo ◽  
A. Kalonji-Mbuyi ◽  
R. V. Kizungu

1999 ◽  
Vol 26 (1) ◽  
pp. 4-8 ◽  
Author(s):  
J. A. Baysinger ◽  
H. A. Melouk ◽  
D. S. Murray

Abstract Early leaf spot is a common disease of peanut caused by the fungus Cercospora arachidicola Hori. Experiments were conducted to evaluate the effect of postemergence herbicides on the conidial germination of C. arachidicola and on the incidence of early leaf spot disease in peanut (Arachis hypogaea L.) in a greenhouse. Conidial germination was enhanced (≥ 100%) at concentrations of 1, 100, and 1000 mg/L of 2,4-DB compared with the untreated control. Lactofen reduced conidial germination by 42% compared with the control at concentrations as low as 100 mg/L and completely inhibited germination at concentrations ≥ 5000 mg/L. A concentration of 10,000 mg/L acifluorfen and 2,4-DB completely inhibited conidial germination. Acifluorfen, acifluorfen plus 2,4-DB, and lactofen decreased the sporulation of early leaf spot lesions. Lactofen reduced leaf spot incidence 12% and decreased sporulation of lesions 22% compared with the control. None of the herbicides increased the incidence of early leaf spot on peanut plants or the number of early leaf spot lesions per leaflet when compared with plants that received no herbicide.


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