ARABLE

Maize pest and disease alerts

12 March 2018

These include:

  • Army worm caterpillars are being observed, especially where grass weeds are present;
  • Be on the lookout for brown marmorated stink bug;
  • Velvetleaf plants are flowering now: Be on the lookout and report any findings;
  • Northern Corn Leaf Blight and Common rust:With the exception of the far North, (now severe), minor infections are generally being observed but also a few more significant outbreaks and growers are advised to continue scouting.

FAR has noted some recent conclusions on maize leaf diseases:

  • Choosing a disease resistance hybrid is the most cost-effective way of avoiding plant disease issues;
  • Late planted maize crops planted adjacent or close to early-planted crops are much more vulnerable to leaf diseases;
  • There is seldom an economic return from applying fungicides at or after silking;
  • If dry conditions prevail during the flowering period, fungicides applied pre-tassel may well provide a yield advantage by improving pollination. Some international research has shown that strobilurin/Qols fungicides can to improve water and nitrogen use efficiency, delay senescence and improve stalk strength;
  • A single fungicide application at growth stage VT (when the last branch of the tassel is visible, but silks have not emerged) appears to be the most cost effective;
  • High water rates (200+l/ha) are more effective at protecting a large leaf area that is not necessarily at the top of the canopy;
  • As with all agrichemicals, it is important to read labels and observe withholding periods, especially for maize silage feed for stock.

Source: FAR