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Plectosporium alismatis is a fungal pathogen that is being investigated as a biocontrol agent for suppressing starfruit (Damasonium minus), a significant weed of Australian rice fields. The aim of this research was to study the effect of the fungus on weed competition and its interactions with chemical herbicides. Conidial germination was significantly reduced by Londax® (bensulfuron-methyl), while MCPA had no effects. Glasshouse trials showed evidence of synergism between the fungus and 1.56% of the recommended dose of Londax®, in reducing the weed growth. The application of inoculum (conidia suspended in water) in the glasshouse eliminated weed competition with rice. In the field, the reduction in weed growth caused by the fungus did not significantly eliminate starfruit competition with rice. This is thought to be due to the presence of other weeds. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the production of chlamydospores and conidia of Rhynchosporium alismatis in a liquid Czapex-Dox based medium supplemented with increasing concentrations of sodium nitrate and malt extract. In addition, the germination of chlamydospores was evaluated. A high concentration of malt extract (4.4 g L -1 ) as the sole carbon source and a high level of sodium nitrate as the sole nitrogen source (3.3 g L -1 ) were shown to increase chlamydospore production while agitation (150 rpm) enhanced conidial yields. Maximum chlamydospore production (2.03×10 5 ±0.7 total chlamydospores mg DW -1 ) was achieved in cultures grown in a medium supplemented with 8.8 g L -1 malt extract and 5.74 g L -1 sodium nitrate. Two days growth was required for maximum chlamydospore and conidial production, while 6 days was necessary to obtain maximum dry weight accumulation (350 mg per flask). Germination of chlamydospores (90%) was significantly higher than germination of conidia (47%) after 2 days growth. [ABSTRACT FROM AUTHOR]

The fungal pathogen Rhynchosporium alismatis is being developed for biological control of starfruit ( Damasonium minus ), an important aquatic weed in Australian rice fields. The development of R. alismatis in starfruit differs between juvenile and adult plants. Juvenile starfruit plants are stunted as a result of fungal infection, while in adult plants, the main effect is necrosis and chlorosis of floating leaves. A conidial concentration of 1×10 4 conidia mL -1 was adequate to cause disease symptoms on floating leaves, but the stunting effect on juveniles was caused by concentrations of at least 1×10 5 conidia mL -1 . To successfully inoculate juvenile plants, the water must be drained before inoculation to expose plants to the inoculum. The artificial addition of dew periods did not enhance disease development in plants. The stunting of juvenile starfruit plants caused by the infection of R. alismatis may give rice plants a competitive advantage over the weed at the seedling stage [ABSTRACT FROM AUTHOR]

Examines the influence of nutrition on conidial production by Rhynchosporium alismatis in Australia. Correlation between image analysis of diseased leaf discs and low visual assessment; Determination on the fitness of Conidia in small-scale biofermentors; Use of bioassay on Alisma lanceolatum leaves.