Prolectus – a new horticultural fungicide

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Based on the active ingredient fenpyrazamine, the fungicide Prolectus has received UK registration and is an important new addition to the armoury for the control of Botrytis in grapes and outdoor strawberries and a range of protected crops.

Prolectus is a new fungicide for the control of grey mould (Botrytis cinerea) in wine grapes, outdoor and protected strawberries, protected crops of tomatoes, aubergines, peppers and in edible peel cucurbits such as cucumbers and courgettes. “In trials, it has also shown good activity on Sclerotinia sclerotiorum, Monilinia and Pseudocercosporella (white leaf spot). It is a non-systemic fungicide with translaminar activity, giving protective as well as significant curative control. It acts by inhibiting germ tube elongation, mycelial growth and has some anti-sporulant properties,” explains Simon Bishop of Nufarm UK.

“In extensive trials and commercial usage in Italy, Prolectus has shown excellent activity against Botrytis, and has performed as well as or better than the standard fungicide treatments currently used. Growers are looking for and will welcome another robust fungicide to integrate into their disease control programmes. In particular Prolectus has strong curative activity which blocks the development of B. cinerea so that it not able to sporulate. Other fungicides used only partially block pathogen development,” explains Simon.

He points out that Botrytis is an easy disease to recognise but it is difficult to control. “It affects all aerial parts of the plant as well as the fruits. It is particularly common during cool, damp weather. Temperatures of 10° to 20°C and a relative humidity of 95% for at least three hours will lead to spore germination. The rate of decay caused by Botrytis depends upon temperature, but generally a huge number of spores are produced.”

In outdoor and protected strawberries, protected tomatoes, aubergines, peppers, cucumbers and courgettes, Prolectus is recommended at 120g/100L water. “It is important to use a sufficient water volume to obtain complete crop coverage, but do not exceed the maximum dose of 1.2 kg product/ha.”

Botrytis control usually requires a programme of fungicide sprays (in strawberries up to 17 sprays according to the Pesticide Usage Survey 2012) and so Prolectus should be used as a part of a programme and sequenced with products with a different mode of action in order to minimise the risk of resistance. To prevent or limit the development of less sensitive Botrytis strains, applications should not be made consecutively but the product should be used in alternation with others having a different mode of action. Fenpyrazamine is a FRAC group 17 (ergosterol biosynthesis inhibitor).

The timing for Prolectus in outdoor and protected strawberries is from first flower open stage until fruits are starting to show a ripe appearance. Prolectus can be sprayed until 1 day before harvest.

In grapes grown for wine, Prolectus is recommended at 1.2 kg/ha in a water rate of 300 to 1000 Litres per hectare. The higher water volumes are used where necessary to achieve good coverage. The timing for wine grapes is from the start of flowering until berries start to ripen. Prolectus can be sprayed until 14 days before harvest in wine grapes.

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