There are numerous fungicide options to control leaf spot and stem rot in peanuts, and more recently, there is research showing that Miravis plus Elatus provides Sclerotinia blight control. Fontelis has activity against Sclerotinia blight as well. Historically, Omega 500 has been the standard for Sclerotinia blight control. While Endura has been around for a long time and has activity against Sclerotinia blight, Omega 500 was the more popular spray for this disease.

The Virginia market types we grow now have some resistance to Sclerotinia blight. Bailey II and Sullivan offer good resistance, and while Emery is more susceptible to disease than Bailey II or Sullivan, it is more resistant than many of the older varieties (NC 12C, CHAMPS, VA 98R, Gregory, NC-V 11, Perry, etc.) In many cases, our rotations are longer and that helps with Sclerotinia blight (and CBR or black root rot, which has diminished significantly in recent years.) We are in a very different world in the V-C region now when it comes to CBR and Sclerotinia blight than we were 10 years ago and especially in the decades before that.

One question I have had is how a Miravis plus Elatus spray should be positioned if one wants to control leaf spot, stem rot, and Sclerotinia blight. Just to be clear, we have many good fungicides that can fit in sprays two, three, and 4 (and 5 if we go with a 6-spray program) for leaf spot and stem rot. Spray one and spray five (or six) needs to have chlorothalonil. Chlorothalonil alone or with a product that has some curative activity is popular for the first spray. The curative part is minor but measurable. The last spray(s) of chlorothalonil are effective on leaf spot and serve as a resistant management tool for all other modes of action when it comes to leaf spot.

Keep in mind that this is a discussion about placement of Miravis and Elatus. Other effective programs exist without the Miravis program. However, here are two possible approaches that include one spray of Miravis plus Elatus. Note that research in Virginia has shown that the combination of Miravis plus Elatus does well on Sclerotinia blight. The contribution of Miravis versus Elatus to control is not well defined. The combination of the two in mixture has proven effective.

Leaf Spot and Stem Rot Control (Sclerotinia blight is not present)

Spray 1 – Chlorothalonil (14 days of protection)

Spray 2 – Miravis plus Elatus (21 days of protection)

Spray 3 – Fungicide(s) with activity against leaf spot and stem rot (14 days of protection)

Spray 4 – Chlorothalonil (add generic tebuconazole or another product for stem rot control if this spray is in August) OR fungicide(s) other than chlorothalonil, Miravis and Elatus that are effective on leaf spot and stem rot (if in August) (14 days of protection)

Spray 5 – Chlorothalonil (14 days of protection)

Leaf Spot, Stem Rot, and Sclerotinia blight control

Spray 1 – Chlorothalonil (14 days of protection)

Spray 2 – Fungicide(s) with activity against leaf spot and stem rot (14 days of protection)

Spray 3 – Miravis plus Elatus (21 days of protection)

Spray 4 – Chlorothalonil (add generic tebuconazole or another product for stem rot control if this spray is in August) OR fungicide(s) other than chlorothalonil, Miravis and Elatus with modes of action different from Miravis and Elatus (14 days of protection)

Spray 5 – Chlorothalonil (14 days of protection)

IMPORTANT

The shift from spray 2 to spray 3 for Miravis plus Elatus is to get this treatment matching more closely to development of Sclerotinia blight. August and September can be very active for this disease and we find that we get the most control with earlier sprays when this disease begins to develop. Applying Miravis plus Elatus around the first week of August will often cover the initial start of Sclerotinia blight. Scout the lower areas of fields for the first signs of this disease to target sprays. The Sclerotinia blight advisory can help time your sprays as well.

We know that excessive sprays of chlorothalonil can increase Sclerotinia blight. One or two sprays should not be an issue, especially with good control in August and the resistance we have in our varieties.

Sequential applications (2 consecutive sprays) of Miravis plus Elatus are also an option. This can be expensive, especially at the 21-day interval suggested above. Data from work in 2021 in North Carolina showed some risk to leaf spot control when a follow up spray after Miravis plus Elatus occurs at 4 or 5 weeks compared with 3 weeks. This changes the economics of the program. However, in fields with a known history of Sclerotinia blight and presence of disease could warrant the sequential applications. Miravis plus Elatus is attractive compared with Omega 500 because of the leaf spot control provided by Miravis plus Elatus. Omega 500 does not protect from leaf spot but does provide protection from stem rot and Sclerotinia blight.

Regardless of the placement of the one spray of Miravis plus Elatus in a program, deciding to make sequential applications of Miravis plus Elatus (2 consecutive sprays), or the interval of time you are relying on for protection provided by Miravis plus Elatus (3 or 4 weeks), it is imperative to apply one or two sprays with modes of action different from Miravis plus Elatus prior to the end of the season and harvest for leaf spot resistance management. This is where one or more applications of chlorothalonil can be essential.