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Foliar application of entomopathogenic nematodes for the control of vine mealybug (Planococcus ficus) in vineyards

by | Oct 18, 2020 | Viticulture

Project Number

P04000078

Project Title

Foliar application of entomopathogenic nematodes for the control of vine mealybug (Planococcus ficus) in vineyards

 

Project Leader

Stokwe, N

 

Team members

Allsopp, E

Malan, A

Williams, L

Hinds, D

Platt, T

 

Completion date

2018

 

EXECUTIVE SUMMARY
Objectives & Rationale
The objectives of this study were to develop protocols for the foliar application of entomopathogenic nematodes (EPN) to control grapevine mealybug, Planococcus ficus, and for assessing the efficacy of foliar EPN applications against mealybug on grapevine leaves; to test EPN efficacy against mealybugs on potted grapevines in glasshouse trials, and to assess the efficacy of EPNs applied to mealybug-infested grapevines at different times under semi-field conditions.
Methods
Laboratory bioassays were performed with four local EPN species to determine their ability to control P. ficus, the minimum time required for optimal infection by S. yirgalemense, and the effects of varying temperature and relative humidity (%RH) on EPN-induced mealybug mortality. The ability of two adjuvants, Zeba® and Nu-Film-P®, to improve the efficacy of S. yirgalemense was tested under semi-controlled conditions and under semi-field conditions.
Key Results
H. noenieputensis was the most effective EPN isolates, causing 90% ± 3% mortality, followed by S. yirgalemense (63% ± 7%), with both causing mortality significantly more significant than the control. Mortality of P. ficus did not improve significantly when exposed to S. yirgalemense for longer than 3h. Mortality of P. ficus was greatest at 25°C (72% ± 3%) and at 100% RH. The addition of Zeba® and Nu-FilmP® to EPN suspensions increased EPN deposition on grapevine leaves and increased the mealybug mortality significantly under semi-field conditions.
Conclusion and Discussion / Recommendation
The critical factor for S. yirgalemense to effectively control mealybug on grapevines appears to be humidity, which must be maximised. Anti-desiccant adjuvants and applications timed to coincide with maximum daily relative humidity levels should be used to achieve the highest relative humidity possible. Other means, such as overhead irrigation and the use of shade netting should also be investigated for their ability to improve the effectiveness of S. yirgalemense on grapevines. The next step will be to test S. yirgalemense with suitable adjuvants in field applications to refine the treatments and application methods into a viable treatment, which can be used in commercial vineyards as part of an integrated pest management system for the control of mealybugs.

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