Recent dry weather has led to sugar beet crops emerging unevenly, making herbicide applications tricky to time.
Pam Chambers, UPL national influencer based near Diss, in Norfolk, says rainfall has been very localised and variable. “Some beet fields look brilliant, starting with their fourth leaves whereas on heavier land where seedbeds are not so good and seeds didn’t hit moisture at the right time they vary from 2-3 leaves to patches where there is nothing.”
However, even where emergence is incomplete, if weeds are present, herbicides should be applied, advises Miss Chambers. “Otherwise they will keep growing and become progressively more difficult to control.”
Some herbicides are harder on the crop than others and if it is just emerging then actives such as triflusulfuron-methyl, lenacil and ethofumesate should be used with caution. Where still being used, desmedipham will also ‘hot’ a mix up, she says.
“Metamitron is renowned for being kind to the crop but also the weeds. In combination with phenmedipham, metamitron can be a useful holding spray that will sensitise weeds to future sprays. Also if weeds are larger they are more difficult to control so after 4-5 days check how the herbicide is working as you may need to tighten spray intervals.”
Although some crops may only be at the expanded cotyledon stage, if fully emerged they will tolerate a more robust herbicide as they will have been hardened off by the cold, dry conditions, she says.
“Fast growing beet will be more vulnerable to damage than beet just sitting there at the moment.”
Where black-grass is an issue, ensure it is actively growing before applying clethodim, she adds. “And in hard water areas there will be a benefit from adding a water conditioner to the spray tank prior to the graminicide.”
BBRO says a dry April and soil pest damage has led to variable germination. Any large blocks of seed which has not germinated needs to be investigated, it advises.