Working with nature to improve the environment and profitability of irrigated cotton production at ‘Kilmarnock’, Namoi Valley, New South Wales

Co-Occurrence of Defoliating and Non-Defoliating Pathotypes of Verticillium Dahliae in Field-Grown Cotton Plants in New South Wales, Australia

Plants ◽

10.3390/plants9060750 ◽

2020 ◽

Vol 9 (6) ◽

pp. 750

Author(s):

Duy P. Le ◽

Aphrika Gregson ◽

Thao T. Tran ◽

Rodney Jackson

Keyword(s):

Verticillium Dahliae ◽

New South ◽

New South Wales ◽

Cotton Production ◽

Major Constraint ◽

South Wales ◽

Cotton Plants ◽

Pot Trials ◽

Germination Traits ◽

Highly Virulent

Verticillium wilt (VW) is a major constraint to cotton production in Australia and worldwide. The disease is caused by a soilborne fungus, Verticillium dahliae, a highly virulent pathogen on cotton. Commonly, V. dahliae is designated into two pathotypes: defoliating (D) and non-defoliating (ND), based on induced symptoms. In the previous two survey seasons between 2017 and 2019, stems with suspected VW were sampled for the confirmation of presence and distribution of D and ND pathotypes across New South Wales (NSW), Australia. A total of 151 and 84 VW-suspected stems sampled from the 2017/18 and 2018/19 seasons, respectively, were subjected to pathogen isolation. Of these, 94 and 57 stems were positive for V. dahliae; and 18 and 20 stems sampled respectively from the two seasons yielded the D pathotype isolates. Two stems from the 2017/18 season and one stem from 2018/19 season yielded both D and ND pathotype isolates. We also successfully demonstrated the co-infection of both pathotypes in pot trials, which was driven predominantly by either of the pathotypes, and appeared independent on vegetative growth, fecundity and spore germination traits. Our study is the first report of the natural co-occurrence of both D and ND pathotypes in same field-grown cotton plants in NSW, to which a challenge to the disease management will be discussed.

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Long-term changes in the numbers of Helicoverpa punctigera (Lepidoptera: Noctuidae) in a cotton production landscape in northern New South Wales, Australia

Bulletin of Entomological Research ◽

10.1017/s0007485316000821 ◽

2016 ◽

Vol 107 (2) ◽

pp. 174-187 ◽

Cited By ~ 3

Author(s):

G.H. Baker ◽

C.R. Tann

Keyword(s):

New South ◽

New South Wales ◽

Habitat Type ◽

Bt Cotton ◽

Cotton Production ◽

Bt Resistance ◽

South Wales ◽

Eastern Australia ◽

Long Term Changes

AbstractTwo noctuid moths, Helicoverpa punctigera and Helicoverpa armigera, are pests of several agricultural crops in Australia, most notably cotton. Cotton is a summer crop, grown predominantly in eastern Australia. The use of transgenic (Bt) cotton has reduced the damage caused by Helicoverpa spp., but the development of Bt resistance in these insects remains a threat. In the past, large populations of H. punctigera have built up in inland Australia, following autumn-winter rains. Moths have then migrated to the cropping regions in spring, when their inland host plants dried off. To determine if there have been any long-term changes in this pattern, pheromone traps were set for H. punctigera throughout a cropping landscape in northern New South Wales from 1992 to 2015. At least three generations of moths were caught from spring to autumn. The 1st generation (mostly spring migrants) was the most numerous. Trap captures varied between sites and decreased in time, especially for moths in the 1st generation. Nearby habitat type influenced the size of catch and there was some evidence that local weather also influenced the numbers of moths caught. There was no correlation between trap catches in the cropping region and rainfall in the inland. In addition, there was little evidence that Bt cotton has reduced the abundance of H. punctigera at landscape scale. The apparent decline in the number of presumably Bt susceptible moths arriving each spring in the cropping regions from inland habitats is of concern in relation to the management of Bt resistance.

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