Cereal Leaf Beetle at Threshold in Some Fields

I had a few calls and emails yesterday about cereal leaf beetle in both winter and spring wheat.  Damage was significant enough even in the winter wheat near Stayner and Bolton to warrant a spray.  These winter wheat fields in particular were still in the earlier heading stages with 5 weeks to go before harvest.  Significant feeding could be seen, particularly on the flag leaf and you could find 1 larvae per stem which is threshold.  Though current thresholds typically state “prior to heading”, recent research from the US has found that feeding even into the earlier heading stages can cause significant yield loss.  I only recommend spraying for cereal leaf beetle in winter wheat if it is still in the earlier heading stages and that you have at least a month prior to harvest because of the days to harvest intervals for many of the products registered in cereals.

Spring wheat should also be scouted.  Report of a field near Seaforth at threshold levels was reported.  If cereal leaf beetle infestations are at threshold, tankmixing your insecticide with your fungicide applications may be appropriate in terms of timing but there could be risks.  Tankmixes with some of these insecticides and the fusarium products have the potential to impact wheat pollination.  There is not a lot of research on these tankmixes to know for sure how safe they are to the crop, particularly during pollination.  Check labels to ensure product compatibility.

Remember temperatures are above 25C this week.  Spraying in the evening is advised as some insecticides are less effective at these higher temperatures.

For more information on cereal leaf beetle and product options, click on these two links:  http://www.omafra.gov.on.ca/english/crops/pub811/13cereal.htm#clbeetle and http://www.omafra.gov.on.ca/english/crops/pub812/p812toc4.html