Overwintering Squash Bugs Harbor and Transmit the Causal Agent of Cucurbit Yellow Vine Disease

2004 ◽  
Vol 97 (1) ◽  
pp. 74-78 ◽  
Author(s):  
S. D. Pair ◽  
B. D. Bruton ◽  
F. Mitchell ◽  
J. Fletcher ◽  
A. Wayadande ◽  
...  
Plant Disease ◽  
2003 ◽  
Vol 87 (8) ◽  
pp. 937-944 ◽  
Author(s):  
B. D. Bruton ◽  
F. Mitchell ◽  
J. Fletcher ◽  
S. D. Pair ◽  
A. Wayadande ◽  
...  

Cucurbit yellow vine disease (CYVD), which can inflict heavy losses to watermelon, pumpkin, cantaloupe, and squash in U.S. production areas from the midwest to northeastern states, causes phloem discoloration, foliar yellowing, wilting, and plant decline. Bacteria were cultured from the phloem of crown sections of symptomatic plants of Citrullus lanatas and Cucurbita pepo. Those bacteria testing positive in CYVD-specific polymerase chain reaction (PCR) were all gram negative and appeared morphologically identical, producing creamy white, smooth, entire, convex colonies on Luria-Bertani or nutrient agar. Characterized cucurbit-derived strains of Serratia marcescens were introduced into greenhouse-grown squash plants by puncture inoculation and into field-grown squash plants by enclosure with S. marcescens-fed squash bugs, Anasa tristis. Up to 60% of the bacteria-inoculated plants in the greenhouse and up to 17% of field plants caged with inoculative squash bugs developed phloem discoloration and tested positive for S. marcescens by CYVD-specific PCR. None of the controls developed phloem discoloration or tested positive by PCR. Of the diseased field plants, 12% (2 of 35) also yellowed, wilted, and collapsed, exhibiting full symptom development of CYVD. However, neither plant collapse nor decline was observed in the greenhouse-grown, puncture-inoculated plants. The morphology, growth habit, and PCR reaction of bacteria cultured from crown tissue of a subset of plants in each experimental group were indistinguishable from those of the inoculum bacteria. Evidence presented from our studies confirms that the squash bug can transmit S. marcescens, the CYVD causal bacterium. The S. marcescens-A. tristis relationship described here is the first instance in which the squash bug has been identified as a vector of a plant pathogen. Our experiments represent a completion of the steps of Koch's postulates, demonstrating that S. marcescens is the causal agent of CYVD and that the squash bug, A. tristis, is a vector of the pathogen.


Planta Medica ◽  
2008 ◽  
Vol 74 (09) ◽  
Author(s):  
HMT Herath ◽  
WHMW Herath ◽  
SO Duke ◽  
M Tomaso-Peterson ◽  
NPD Nanayakkara

Planta Medica ◽  
2007 ◽  
Vol 73 (09) ◽  
Author(s):  
JM Rollinger ◽  
R Spitaler ◽  
M Menz ◽  
P Schneider ◽  
EP Ellmerer ◽  
...  

Author(s):  
A. Muntala ◽  
P. M. Norshie ◽  
K. G. Santo ◽  
C. K. S. Saba

A survey was conducted in twenty-five cashew (Anacardium occidentale) orchards in five communities in the Dormaa-Central Municipality of Bono Region of Ghana to assess the incidence and severity of anthracnose, gummosis and die-back diseases on cashew. Cashew diseased samples of leaves, stem, inflorescences, twigs, flowers, nuts and apples showing symptoms (e. g. small, water-soaked, circular or irregular yellow, dark or brown spots or lesions on leaves, fruits and flowers, sunken surface, especially on the apples, blight, gum exudates) were collected for isolation of presumptive causative organism. The pathogen was isolated after disinfecting the excised diseased pieces in 70% ethanol, plated on potato dextrose agar (PDA) and incubated at 28 oC for 3 to 7 days. The identity of the putative pathogen was morphologically and culturally confirmed as belonging to Colletotrichum gloeosporioides species complex using standard mycological identification protocols. The pathogen had varied conidia sizes of between 9-15 up to 20 μm in length and diameter of 3-6 μm. The conidia were straight and cylindrically shaped with rounded or obtuse ends. The septate mycelium was whitish-grey, velvety and cotton-like in appearance from the top. The results confirmed the presence of the pathogen in the orchards with incidence ranging from 6.9% and 14.0% for gummosis and averaged 22.9% for anthracnose infected orchards. The result of the pathogenicity test confirmed the isolates to be pathogenic on inoculated cashew seedlings and were consistently re-isolated, thereby establishing the pathogen as the true causal agent of the said diseases in cashew trees and thus completed the Koch’s postulate.


Author(s):  
Mladen Petres ◽  
Marta Loc ◽  
Mila Grahovac ◽  
Vera Stojsin ◽  
Dragana Budakov ◽  
...  

2018 ◽  
Vol 96 (10) ◽  
pp. 27-34
Author(s):  
M. Musiienko ◽  
L. Batsmanova ◽  
Ju. Pys'menna ◽  
T. Kondratiuk ◽  
N. Taran ◽  
...  

1998 ◽  
Vol 64 (5) ◽  
pp. 451-457 ◽  
Author(s):  
Susumu TAKAMATSU ◽  
Manami NAKANO ◽  
Hideyuki YOKOTA ◽  
Hitoshi KUNOH

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