Host range of Puccinia xanthii and postpenetration development on Xanthium occidentale

1993 ◽  
Vol 71 (7) ◽  
pp. 959-965 ◽  
Author(s):  
Louise Morin ◽  
Bruce A. Auld ◽  
John F. Brown
Keyword(s):  
Key Words ◽  
Host Range ◽  
Weed Control ◽  
Biological Weed Control ◽  
Controlled Environment ◽  
Globe Artichoke ◽  
Disease Symptoms ◽  
Severity Of The Disease ◽  
Stem Lesions ◽  
Slow Growing

In glasshouse studies, small necrotic foliar flecks developed on globe artichoke, calendula, slender thistle, and winged slender thistle following inoculation with basidiospores of the microcyclic rust Puccinia xanthii. Fourteen inoculated cultivars of sunflower developed various types of symptoms: small necrotic and chlorotic flecks, underdeveloped telia, and small swollen petiole and stem lesions. Xanthium spinosum developed very slow-growing telia. In controlled environment studies, the four Xanthium spp. comprising the Noogoora burr (cocklebur) complex in Australia were highly susceptible to infection by P. xanthii. Maximum disease severity was observed after rust telia and X. occidentale plants were exposed to a dew period of 24 h. Less disease symptoms were observed in plants exposed to shorter (3, 6, 12 h) or longer (36 h) dew periods. Plants inoculated with several loads of inoculum (exposure to four inoculum plates) were less diseased than plants inoculated with fewer inoculum loads. Infected plants began to develop disease symptoms 5 days after inoculation, when grown at 25 °C. Infected plants developed very few small chlorotic flecks and no disease symptoms when grown at 10 and 40 °C, respectively. The flecks produced on plants kept at 10 °C developed into telia when plants were transferred to a glasshouse (25 °C). Repetitive inoculations of plants for 1 month increased the overall severity of the disease and this resulted in a reduction in plant height. Key words: Xanthium, host range, Puccinia xanthii, biological weed control.

scholarly journals First Report of Colletotrichum truncatum Causing Stem Cankers on Jatropha curcas in Burkina Faso

Plant Disease ◽  
2015 ◽  
Vol 99 (1) ◽  
pp. 14-20 ◽  
Author(s):  
C. A. Ellison ◽  
A. Sawadogo ◽  
S. Braman ◽  
S. Nacro
Keyword(s):  
Burkina Faso ◽  
Jatropha Curcas ◽  
Management Practices ◽  
Fruit Production ◽  
Multiple Infections ◽  
Colletotrichum Truncatum ◽  
Yield Losses ◽  
Disease Symptoms ◽  
Stem Lesions ◽  
Stem Cankers

A new disease was identified on the biofuel crop Jatropha curcas in 2012 in Burkina Faso that is causing serious yield losses. The disease was found to be widespread in both Sissili and Comoé Provinces. It causes characteristic leaf lesions, fruit necrosis, and cankers on young stems and branches. There was evidence of multiple infections on plants over the growing season, with regrowth evident from below old cankers, but there was little fruit production from infected branches. A detailed monitoring and assessment was undertaken of the disease progress in a severely infected field, over a 7-week period. The disease symptoms progressed from chlorosis through a necrotic phase and, in approximately 83% of replicates, stem cankers developed that resulted in dieback and lodging of branches. Colletotrichum truncatum and a member of the species complex C. gloeosporioides sensu lato were consistently isolated from fresh stem samples showing early symptoms (chlorosis). Koch's postulates were undertaken, to establish the pathogenicity of the two species. No symptoms were observed on plants inoculated with C. gloeosporioides; however, leaf and stem lesions developed after inoculation with C. truncatum, which was reisolated from the diseased tissue, confirming it as the disease-causing agent. Preliminary management practices for the disease are proposed.

Response of lowbush blueberry (Vaccinium angustifolium) to hexazinone applied early in the fruiting year

2002 ◽  
Vol 82 (4) ◽  
pp. 781-783 ◽  
Author(s):  
K. I. N. Jensen ◽  
E. G. Specht
Keyword(s):  
Key Words ◽  
Weed Control ◽  
Corolla Tube ◽  
Growth Stages ◽  
Vaccinium Angustifolium ◽  
Floral Buds ◽  
Perennial Weeds ◽  
Lowbush Blueberry ◽  
Herbaceous Perennial

Spring application of 1.0 kg ha-1 hexazinone to fruiting-year lowbush blueberry no later than the F3 floral stage, when floral buds separate, but before the corolla tube shows white, controlled some common herbaceous perennial weeds without injury to the crop. Key words: Herbicide injury, growth stages, weed control, hexazinone, Vaccinium angustifolium

SENSITIVITY AND ADAPTATION OF SELECTED RHIZOBIA AND AGROBACTERIA TO PARAQUAT

1985 ◽  
Vol 65 (3) ◽  
pp. 555-562 ◽  
Author(s):  
E. B. ROSLYCKY
Keyword(s):  
Key Words ◽  
Genetic Effect ◽  
Agrobacterium Radiobacter ◽  
Plant Weight ◽  
Fast Growing ◽  
Plant Symbiont ◽  
Paraquat Resistance ◽  
Rhizobium Lupini ◽  
The Relationship ◽  
Slow Growing

Sensitivity to paraquat as function of growth varied considerably among 15 rhizobia from seven cross-inoculation groups and 13 agrobacteria from five different species. No relationship was evident between the sensitivity and the "fast-growing" or the "slow-growing" characteristics among the rhizobia. The agrobacteria were uniformly less sensitive. Maximum stabilized paraquat resistance induced by the adptations ranged from 200 μg paraquat∙mL−1 in Rhizobium lupini 112, to 20 000 μg paraquat∙mL−1 in Agrobacterium radiobacter R-590 and A. tumefaciens A6-K1. No relationship was found between the sensitivity and the adaptability. Identical lytic patterns with six bacteriophages confirmed the relationship between the adapted and parent cultures suggesting no genetic effect of paraquat on susceptibility to lysis. The bacteria-plant symbiont interaction, including nodulation, plant weight, vigor and color, was unaffected by the adaptations to paraquat resistance. Similarly, the adaptations exerted no effect on tumorigenicity of A. tumefaciens A6-K1. Key words: Rhizobia, agrobacteria, adaptation, herbicides, paraquat, N2-fixation

scholarly journals Effect of the concentration of inoculum and tensoactive on the efficiency of Bipolaris sorokiniana infection in wheat leaves

2014 ◽  
Vol 40 (2) ◽  
pp. 178-181 ◽  
Author(s):  
Erlei Melo Reis ◽  
Tiago Zanatta ◽  
Anderson L. Danelli
Keyword(s):  
Disease Severity ◽  
Fungal Spores ◽  
Bipolaris Sorokiniana ◽  
Inoculum Density ◽  
Tween 20 ◽  
Controlled Environment ◽  
Wheat Cultivars ◽  
Infection Rates ◽  
Wheat Leaves ◽  
Severity Of The Disease

Techniques that result in increased pathogen infection rates by employing reduced quantities of fungal spores with sparse sporulation have been developed. Experiments under controlled environment conditions were conducted to evaluate the effect of the density of Bipolaris sorokiniana conidia on the intensity of wheat helminthosporiosis. Using a selected inoculum density, the concentration of the tensoactive (Tween 20) that promoted maximum infection by the causal agent of the disease was determined. The density of lesions and the estimated severity of the disease were quantified. The selected inoculum density was 1.5 x 10(4) spores.mL-1 plus 480 µL tensoactive.L-1 water, resulting in a disease severity that allows selecting wheat cultivars resistant to B. sorokiniana.

scholarly journals Safety in New Zealand weed biocontrol a nationwide pathogen survey for impacts on nontarget plants

2009 ◽  
Vol 62 ◽  
pp. 41-49 ◽  
Author(s):  
N.W. Waipara ◽  
J. Barton ◽  
L.A. Smith ◽  
H.M. Harman ◽  
C.J. Winks ◽  
...  
Keyword(s):  
New Zealand ◽  
Host Range ◽  
Plant Pathogens ◽  
Research Programme ◽  
Disease Symptoms ◽  
Weed Biocontrol ◽  
Disease Surveys ◽  
Rubus Species ◽  
Disease Damage ◽  
Range Testing

The accuracy of host range testing in weed biocontrol programmes using plant pathogens has been questioned prompting a research programme into the field safety record of pathogens used for weed biocontrol in New Zealand Nationwide disease surveys were conducted from 20002009 and focused on species closely related to target weeds and therefore potentially most at risk of attack These surveys identified pathogens associated with any disease symptoms observed on nontarget hosts Disease damage attributable to biocontrol agents was observed on two nontarget plants Pustules of the blackberry rust Phragmidium violaceum were found on the endemic Rubus species R cissoides (bush lawyer tataramoa) at one location This result was predicted from host range safety tests conducted prior to its arrival in New Zealand No nontarget damage was observed in the remaining case studies confirming to date that all biocontrol pathogens are highly host specific to their target weeds

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