1. Three weeks to go until you are projected to dig the peanuts and little-or-no disease in the field? I wouldn’t put out any more fungicides unless there is threat of a hurricane or tropical storm. If you are three of more weeks out and on your last spray and you are seeing some leaf spot develop, applying a pint of chlorothalonil TANK-MIXED with 7.2 fl oz of tebuconazole or 5.5 fl oz of Alto (NOTE 30 day PHI for Alto) or 5 fl oz of Topsin or 2.5 fl oz of Domark. If time for your last spray and very little leaf spot is present, then 1.5 pints of chlorothalonil may be all you need.
In 2020, white mold is likely active in your field late in the season. If the white mold is confined to individual plants scattered across the field, then you may want to mix tebuconazole with your last leaf spot spray for some late-season “insurance”. If the disease is more severe, or you are really worried about it, then you might consider using a more effective product. Many growers are considering using Convoy. Please NOTE that the PHI for Convoy (and Umbra) is 40 days before harvest (there is a a misprint in the Pest Control Handbook which I am correcting for 2021). I have included below “pre-harvest intervals” for many of the fungicides you may consider using late in the season.
It is generally advisable to wait to dig the peanuts until they are “ready” based upon the hull-scrape test. This is true even if there is significant Tomato spotted wilt in the field or some white mold. HOWEVER: if there is significant defoliation from leaf spot or significant white mold in the field, it often best to dig the peanuts earlier than planned to avoid excessive digging losses.
Fungicide Pre-Harvest Intervals for Peanuts (note: there is some discussion on whether this means “dug” or “picked”)
Chlorothalonil: 14 days PHI
Domark: 14 day PHI
Topsin M: 14 days PHI
Alto: 30 days PHI
Priaxor: 14 day PHI
Aproach Prima: 30 day PHI
Muscle ADV (tebuconazole + chlorothalonol): 14 days PHI
Abound (azoxystrobin): 14 day PHI
Fontelis: 14 day PHI
Lucento: 14 day PHI
Elatus: 30 day PHI
Convoy: 40 day PHI
Umbra: 40 day PHI