White mould, caused by Sclerotinia sclerotiorum, is a major disease problem of both green and navy beans, causing yield losses by premature plant death through lower stem infection, and/or infection of beans.
Green bean crops with greater than 8% Sclerotinia are rejected due to difficulties in processing.
Thisproject identified :
- the cause of poor Sclerotinia control in the field
- review new developments in Sclerotinia control on other crops
- identified alternative control products
- improve methods for Sclerotinia control.
Fungicide application methods and timing :
A survey of bean growers showed that application methods are highly variable between growers, and that, along with different weather conditions, location and cultural practices, can influence the level of Sclerotinia control.
- When using a boom sprayer, spray water volumes ranging from about 150 to 400L/ha appear to be adequate, when applied at the early flowering period.
- Early fungicide applications, at 5 to 10% plants with first flowers and before canopy becomes dense, give optimum disease control.
- The recommendations on the labels of Benlate and Sumisclex, to spray when 75% plants first show open flowers, need to be reviewed.
- In areas prone to severe Sclerotinia disease, cultural practices, such as low planting density, wider row spacing, and bean varieties, that can assist in reducing conditions conducive to disease development, should be considered.
- In areas that are not prone to severe Sclerotinia infections, an increase in planting density in conjunction with the use of appropriate fungicide and spray methods, could significantly increase yield per hectare.
- Fungicides based on procymidone, Sumisclex and Fortress, are still the most effective products for control of Sclerotinia in bean crops.
- Carbendazim (Spin Flo and Bavistin) appears to give better disease control than benomyl (Benlate), and may be a suitable alternative to benomyl for use in alternation with procymidone.
- Biocontrol agents need to be evaluated in long-term studies to properly determine their potential for Sclerotinia disease control, especially for reducing the level of sclerotia in soil.
The research contained in this report was funded by the Horticultural Research & Development Corporation, with the financial support of:
- Crop Care Australasia Pty Ltd
- Abbott Laboratories
- Rhone-Poulenc Rural Australia Pty Ltd
The Australian Government provides matched funding for all HAL’s R&D activities.