PGRO Crop Bulletin
Number 1. 8th March 2011
Winter bean crops
Some crops of winter beans are showing signs of stress due to the cold weather conditions experienced over the winter months. Severe frost may have caused expansion of wet soil leading to crushed stems which are now turning black and rotting away. Some plants may die off completely. Where the remaining population of beans is greater than 10 plants per square metre the crop should recover sufficiently.
Sowing rate of spring beans and peas
High density beans compete with each other for light and nutrients and result in low yield and high disease risk. The optimum density is 40 plants per sq m established. Use the following to calculate seed rate. (Allow for a 5 - 10% seed bed loss).
Required population x 1000seed weight x 100
% germination 100 – seed bed loss
The calculation is used for peas and optimum plant populations are as follows:
Marrowfats – 65 plants per square m
Large blues and whites – 70 plants per square m
Small blues (Zero 4) – 110 plants per square m
Pre-emergence herbicides
Spring beans and peas are being drilled. Cost effective pre-emergence herbicide options are very much dependent on moisture availability, and additional factors such as cloddy seed beds can also influence whether good or average weed control is achieved.
Some crops of spring beans are not rolled following drilling and some may not need it. Rolling helps conserve moisture and break up clods, giving a level surface to ensure the best ground coverage is achieved with the residual herbicide. If the surface is cloddy then application of pre-emergence herbicides with appropriate angled nozzles may help.
There are various pre-emergence products and tank mixes which can be considered in combining pea and spring bean crops. Newer products perhaps to consider along with Nirvana, Skirmish, Centium, pendimethalin (SOLA beans) and Defy (SOLA beans only) are Afalon (linuron) and Linzone/Lingo (linuron + clomazone). Both are approved for use in combining peas and spring beans.
PGRO technical information
All PGRO Technical Updates have been revised to include the changes in pesticide availability for peas and beans. PGRO publications are available as free downloads from the PGRO web site. User passwords are available on request through the web site.
CB1101.doc