ORCID Profile
0000-0002-2117-0469
Current Organisation
NSW Department of Primary Industries
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Publisher: Elsevier BV
Date: 05-2021
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CP18093
Abstract: Early-season leaf loss due to damage by thrips (Thysanoptera: Thripidae) is considered an important issue by Australian cotton growers. To understand the potential impact of early-season leaf loss in the southern region of New South Wales, we investigated the effects of artificial defoliation on cotton growth, maturity timing and lint yield over four seasons (2013–14 to 2016–17) in commercial cotton crops in the Riverina district. Four defoliation scenarios were investigated: (i) complete defoliation, 100% removal of all true leaves from all plants (ii) partial defoliation by plant, 100% removal of all true leaves from 75% of plants (iii) partial defoliation by leaf, removal of 75% of leaf area from all in idual true leaves on all plants and (iv) no defoliation. Defoliation was done by hand at the onset of the 2-, 4-, and 6-node growth stages. Defoliated plants were initially shorter than undefoliated (control) plants, but by ~100-days post seedling emergence, height differences were no longer statistically significant in two of the four seasons. Defoliation did not affect the total number of bolls shortly before harvest. However, complete defoliation delayed crop maturity by up to 18 days and partial defoliation by plant delayed crop maturity by up to 8 days. Because of the delays, fully defoliated plants often had fewer open bolls shortly before harvest and yielded significantly less than undefoliated plants in three of the four seasons. A laboratory experiment with caged cotton seedlings showed that weekly introductions of up to10 thrips per seedling (predominantly onion thrips (Thrips tabaci), the most abundant species on cotton in the region) caused significant clubbing in true leaves, but the total leaf area was not significantly reduced at the 6-node stage. Implications of the results for southern cotton integrated pest management are discussed.
Publisher: Elsevier BV
Date: 12-2023
Publisher: Wiley
Date: 24-11-2021
DOI: 10.1002/PS.6711
Abstract: The common armyworm Mythimna convecta is an important pest of pastures and graminaceous crops in Australia, but materials currently registered for its control are limited to broad‐spectrum compounds incompatible with integrated pest management (IPM) systems. In this study we assessed the response of M. convecta larvae to four alternative compounds using topical and dietary bioassays. Emamectin benzoate [LC 50 (lethal concentration for 50% of insects tested) values 2.69 μg mL −1 topical, 0.017 μg active ingredient (AI) g −1 dietary] and chlorantraniliprole (LC 50 values 4.87 μg mL −1 topical, 0.080 μg AI g −1 dietary) were significantly more active than either indoxacarb or cyantraniliprole. Our results showed strong parallels with data on the more extensively studied Australian strains of Helicoverpa armigera , with the most notable differences being the higher contact toxicity of emamectin benzoate to M. convecta and the lower acute dietary activity of formulated cyantraniliprole to this species, which was linked to feeding deterrence. Cyantraniliprole at dietary concentrations of ≥0.02 μg AI g −1 significantly reduced the weight of surviving larvae and frass production (an indirect measure of food consumption) over the seven‐day exposure period. There was also some evidence of chlorantraniliprole deterring larval feeding, although to a much more limited extent. Both emamectin benzoate and chlorantraniliprole are suitable for use against M. convecta . The decision as to which of these compounds should be prioritized for further development should be based on their potential effects on beneficial species once their optimal field rates have been determined.
No related grants have been discovered for Jianhua Mo.