When I look at how small my peanuts are today, spraying them for leaf spot seems hard to imagine. We’re at least 40% behind in peanut heat units compared to previous years. Slow, late development tells me we will likely be digging peanuts later than usual. How does that affect initial fungicide spray program decisions?
To me, digging later means there’s potential to apply more fungicide sprays, which can get expensive. My response to late-developing peanuts is to delay the first leaf spot application. The rule of thumb NC and VA have used for initiating leaf spot fungicide programs is 60 DAP (days after planting), but no later than July 10th. But with peanuts so far behind I’d consider shifting that back to no sooner than July 15th, maybe a little later to extend disease control later in this season and to avoid “extra” leaf spot sprays. Not only for leaf spot, but also for soilborne diseases like SSR (southern stem rot/white mold) and SB (Sclerotinia blight). This may be especially true for SB as temperatures cool down as we approach harvest and cool temps favor SB. Saving expensive SB fungicide applications in lieu of a later harvest makes sense to me. I recommend keeping up with peanut heat units and the leaf spot and SB advisories on the Peanut Cotton InfoNet (url link here) or call the Peanut Hotline at 1-800-795-0700. That way you can gage peanut maturity and disease risk to help make fungicide timing decisions.
If questions arise concerning peanut disease management this season please don’t hesitate to reach out to me. My contact info is below:
address: 6321 Holland Rd., Suffolk, VA 23437 office phone: (757) 807-6536; mobile phone (preferred): (757) 870-8498 email: dblangston@vt.edu