Like every year, I get a lot of questions on late leaf spot fungicides the closer we get to digging. Since it’s near the end of the season, regardless if you’ve been on a rigorous, effective leaf spot program you’re going to see some leaf spot. I’ve heard some growers are having severe leaf spot and some significant defoliation. Below I’ll cover some points regarding late leaf spot management as we approach digging.

1. Leaf spot has a greater affect on yield the earlier it occurs.  If the onset of disease begins near harvest we often don’t observe much loss.  I’d be more concerned about yield loss in fields where leaf spot was significantly spreading in early to mid-August compared to just seeing it get worse since labor day weekend.  However, if you see up to 40% or more defoliation, a fungicide application at that point isn’t going to help and you may consider digging early to help preserve yield.
2. The cooler it gets leaf spot takes longer to spread.  Cooler weather coupled with the extremely dry weather we’re experiencing really slows disease development.  The big increases in leaf spot you’re seeing now are the result of infections that took place 2-3 weeks ago or more.  That would mean the fungicide applications you made (or not) early to mid-August are impacting what you’re seeing now more than sprays you applied within the past 2 weeks.  Applying a fungicide now won’t have a major impact on leaf spot or yield.
3. Just because I just said spraying leaf spot now won’t have a big effect on yield doesn’t mean spraying for leaf spot is a terrible idea right now.  A lot of that depends on how close you are to digging based on peanut maturity.  If you’re over 2 weeks away from digging I can see where a fungicide application may help leaves stay on longer and prevent yield loss compared to peanuts that are within 2-weeks of digging.  Everyone’s maturity situation is different, and it can vary from field to field.  The situation is very different between dryland and irrigated peanuts.  In talking to Jacob Forehand in Virginia and David Jordan in NC this morning, according to pod blasting results, peanuts are not maturing very quickly due to cool, dry conditions and peanuts may be mature a little later than “normal”.  Plus, although the forecast isn’t calling for much rain, if it becomes warmer and we get some unexpected rain that can change things so far as maturity and diseases are concerned.  Lots to consider…
4. If you’re going to use a fungicide this late, make sure it’s a fungicide that’s going to be effective (kinda intuitive I know).  I hear about a lot of people making fungicide recommendations that are questionable.  If you ask me about a fungicide to use right now I’m going to tell you to use Provost Silver or chlorothalonil (Bravo, Echo, Equus etc) with or without micronized sulfur.  Why those?  They are the only fungicides that I am confident in providing some control.  The efficacy and curative activity of Provost Silver is well established, chlorothalonil works as well as it did when it was first used back in the 70’s because it has multiple modes of action and carries practically no risk of resistance development, and micronized sulfur has been shown by several researchers in several states to enhance the efficacy of leaf spot applications when mixed with an effective fungicide.  Each product has some downsides which may be a cause for pause. 
5. We use FRAC Group 3 fungicides in almost every application we make on peanuts, and the actives in Provost Silver are both groups 3’s.  Provost Silver is probably the most used FRAC Group 3 fungicide.  The more we use the same MOA (mode of action) over and over again we put more pressure on them for resistance development.  Couple that with spraying when higher inoculum levels are present during the late season adds more to the resistance risk. 
6. Chlorothalonil has been shown to increase the risk of spider mite development, and to a lesser degree it can enhance the development of Sclerotinia blight.  As dry as it is I can see growers being resistant to use chlorothalonil because of spider mites.  But since sulfur has some activity against spider mites, I’ve been suggesting tank-mixing it with chlorothalonil to provide some control of spider mites.  Spider mites are favored by hot, dry conditions.  We have the “dry” but don’t have the “hot” right now and looking forward.  I’m not saying there’s no risk of spider mite infestations right now, but conditions are less favorable for them to occur.
7. The main issue with sulfur are problems with mixing and it’s potential to leave residues in spraying equipment that can cause clogging.  I recommend trying different formulations of micronized sulfur.  The one’s I’m familiar with are Microthiol Disperss® (dry), Kolla® (liquid), and Suffa® (liquid).  I keep using the word “micronized” for a reason.  That is that all the positive efficacy data I talked about earlier was with micronized formulations only.  Non-micronized sulfur does not show the same positive effects on leaf spot control.

With as hot as it’s been in July, it’s hard to imagine Sclerotinia blight showing up in peanuts. I have been searching for it in my trials but haven’t seen it yet. However, highs in the low 80s and lows around 70 today through next week means conditions will be favorable for disease development. Plus, adequate soil moisture is present due to recent rains and peanut canopies are dense enough to favor Sclerotinia blight. I recommend monitoring the Virginia Sclerotinia Blight Advisory on the Peanut Cotton InfoNet to check the risk of this disease in your area and scout for disease, especially in fields with a history of Sclerotinia blight. Access the Peanut Cotton InfoNet using this link https://infonet.ext.vt.edu/. You can also call the VA Peanut Hotline at 1-800-795-0700 for up-to-date disease advisories.

At this point in the season I recommend fungicides Omega or Vantana tank-mixed with a leaf spot fungicide if you haven’t already applied Miravis + Elatus. I hesitate to recommend the first application of Miravis + Elatus this late in the season due to concerns about late leaf spot escapes as these products have no curative activity against leaf spot. You’re okay if it’s the second application. Fontelis at 1.5 pt/acre can provide some disease suppression if sprayed preventively.

Please contact me if you have questions.

David Langston. (757) 870-0498 cell email: dblangston@vt.edu

David Langston 07/09/2025

Peanuts are growing fast and that first leaf spot spray has been applied or should be soon.  Typically folks go with Bravo (1.5 pt), Alto + 1.0 pt Bravo, or Aproach Prima + 1.0 pt Bravo with or without tebuconazole.  With the weekly rain and high humidity, conditions for leaf spot are favorable.  Some folks are thinking about their second spray pretty soon.  Fungicides I like for the second spray are Provysol + tebuconazole, Lucento, Fontelis (1.0 pt) or Miravis.  If you have fields with a history of southern stem rot (white mold) you may need to tank mix the leaf spot fungicide with Convoy, Elatus or Excalia or bump the Fontelis rate up to 1.5 pts.  I’d plan on the third spray being Bravo at 1.5 pt + tebuconazole or substitute tebuconazole with one of the so. stem rot fungicides above.  The fourth spray I like Provost Silver because of it’s “kick-back”/curative activity.  The last spray or last two sprays can be either Provost Silver again or Bravo at 1.5 pt + tebuconazole.  If you think there may be issues with Sclerotinia blight, Omega/Vantana can be used, preferably at disease onset or before, or a second spray of Miravis + Elatus.  Don’t be afraid to use Bravo a couple of times as it doesn’t increase Sclerotinia blight unless it’s sprayed 4-5 times.  However, if it turns hot and dry you should avoid Bravo as it can flare spider mites.

The Situation

I have heard from several growers and county agents that they have been seeing a lot of moldy ears lately.  Unfortunately, the drought in June followed by wet conditions in July and early August set the stage for ear rot fungi to infest corn this year. Ear rot diseases are Aspergillus ear rot, Diplodia ear rot, Fusarium ear rot, Gibberella ear rot, Penicillium ear rot and Trichoderma ear rot.  Pictures and symptoms and signs of each are below.

Aspergillus ear rot

Image by A. Robertson

Diplodia ear rot

Image by G. Munkvold

Fusarium ear rot

Image by A. Robertson

Starburst kernel pattern from Fusarium ear rot

Image by Pioneer Seeds

Gibberella ear rot

Image by A. Robertson

Penicillium ear rot

Image by A. Robertson

Trichoderma ear rot

Image by G. Munkvold

Damage Caused by Ear Rots

The most obvious losses due to ear rots are to yield and quality.  Probably the biggest concern with ear rots is that some of them produce mycotoxins that harm humans and livestock. Mycotoxin producers are Aspergillus ear rot (aflatoxin), Fusarium ear rot (fumonisin), Gibberella ear rot (deoxynivalenol or DON) and to a lesser degree Penicillium ear rot (PR toxin and Ochratoxin A).  Grain cannot be sold for food or feed if aflatoxin levels are 20 ppb (parts per billion), fumonisin levels cannot be higher than 30-50 ppb and DON no higher than 5 ppb.

Assessing Damage

Growers should hand pick 100 ears of corn from a representative area of a field and shuck them.   Pick out 10 ears showing the worst ear rot damage. Place these ears side-by-side to assess the average amount of kernel damage. If more than 25% of the kernels on these 10 ears are damaged, you have a problem.  If less than 25% of kernels on the 10 worst ears are damaged, check the field again after a rainfall event and plan on harvesting early. Harvesting at more than 20% moisture and drying to less than 15% moisture will significantly reduce harvest losses when compared to waiting for the corn to dry on its own in the field.  The extent of the problem can be determined by shelling all 100 ears, mixing the grain thoroughly, and sending a sample (usually 5.0 lbs) to a reputable mycotoxin testing facility.  Don’t mix grain from a field affected by ear rots with grain from a field that has not been affected.

What to do if You Have 10% or More Affected Ears

• Harvest early at higher moisture and dry to below 15% moisture
• Adjust combine to discard light or damaged kernels
• Clean harvest equipment between affected fields and clean fields
• Segregate poor quality grain from good grain
• Store affected long-term grain at less than 13% moisture and 30°F or below
• Don’t store affected grain for more than 1 year

A few disease issues have popped up within the past week on peanuts and soybeans. Some are pretty routine and some are not…

Peanuts

As you may expect, the wet, humid weather has been favorable for peanut diseases like leaf spot, southern stem rot (white mold) and Sclerotinia blight, but especially leaf spot. Sclerotinia is moving slowly due to the warmer weather over past two weeks, but with highs in the 70s today and possibly going forward I expect it to move faster. I have observed Sclerotinia blight in my trial plots. This late in the game I prefer Omega 500 for Sclerotinia blight over Miravis + Elatus. Miravis may not perform against leaf spot if there’s any out there already and Elatus is not a good stand-alone product for Sclerotinia. Remember, if you use Omega 500 you must use a leaf spot material with it. With leaf spot, just don’t extend your spray interval beyond 14 days. The leaf spot advisory has shown leaf spot risk to be steadily high and the last effective spray date jumps 2 days every day. If leaf spot is already showing up you may want to use a micronized sulfur product to temporarily arrest leaf spot along with a fungicide that gives residual control. The hot weather we experienced up until now has led to southern stem rot (white mold) showing up in some fields. If this is the case the best products for that are Excalia (3.0 fl oz), Elatus (7.0 – 9.0 oz) or Convoy at 32 fl oz.

Soybeans

Warm humid weather have led to outbreaks of FLS (frogeye leaf spot) and target spot in some fields. Frogeye will show up first in soybeans that have poor resistance to FLS, and some soybean varieties are more susceptible to target spot like AG49XF3. Both diseases can be very similar in appearance but FLS shows up more in the upper canopy and target spot starts in the lower canopy. I have seen pictures of soybeans defoliated from the bottom up by target spot recently. If you sprayed ahead of disease symptoms you shouldn’t have many problems, but you may see target spot start showing up. If you see disease is already there, use products that have an effective Group 3 fungicide that have curative disease activity. Examples would be Delaro Complete, Lucento, Revylok and Topguard or Topguard EQ.

If you have questions or concerns contact me via e-mail at dblangston@vt.edu or use my cell phone at (757) 870-8498.

With current rainfall from Idalia and cooler temperatures over the next three days, peanut fields with a history of SB (Sclerotinia blight) should be sprayed soon with a fungicide that can reduce losses to that disease.

SB is favored by rainfall and periods of high relative humidity, but what really triggers it is cooler temperatures. The current forecast is for daily highs to be in the upper 70s and 55 to 60° lows over the next three days. Those lows will really get SB cranked up! I have already seen SB slowly moving in my trials and I’ve heard reports that peanut growers are seeing it in some of their fields. According to Dr. David Jordan, peanuts are likely 1 week behind in maturity compared to last year due to the record cool temperatures observed in May, so there’s plenty of time for SB to do some damage.

This late in the game the second spray of Miravis tank-mixed with Elatus surely has been applied, or is about to based on when the first spray was applied. I do not recommend the first application of the Miravis/Elatus tank-mix be used this late, mainly due to it’s having no curative activity on either LLS (late leaf spot) or SB and for reducing risk of fungicide resistance to those chemistries. I’m quite hesitant even to recommend the second application at this time.

The safe bet is applying Omega 500 for SB tank-mixed with an effective fungicide for LLS. If you sprayed Miravis/Elatus the first week of August, I’d prefer to use Omega 500 at 1.0 pt/acre in the next few days to protect against SB. If you have a field that’s notorious for severe losses to SB, you can go to 1.5 pt/acre, but I haven’t seen a big difference in control between the two rates. I consider Omega 500 to have 3 weeks of activity against SB. So if it’s been 3 weeks or more since you applied Omega 500, I’d be thinking about that 2nd application right about now. Remember, Omega 500 has a 30 day PHI (preharvest interval). That’s 30 days prior to harvesting with a peanut picker, not 30 days until digging.

One saving grace is that temperatures go up again next Monday and maintain daily lows in the upper 60s/low 70s and highs in the upper 80s/low 90s until about September 11th according to the current forecast. Most peanuts in the region have fairly dense canopies now, so while the higher temperatures may slow SB development, the disease will continue to progress and potentially explode again if favorable conditions present themselves.

Within the past week two outbreaks of FLS (frogeye leaf spot) have been reported in southeastern Virginia. Southeastern Virginia has experienced warm, humid conditions and frequent rain events which favor FLS development. Both outbreaks were found on soybean varieties susceptible to FLS in the R1 stage. This creates an issue as the recommendation for fungicide timing on soybeans is R3-R5. Having disease already in the field is also less than ideal as fungicides perform better if applied prior to symptom development. To deal with this situation I recommend:

Scout fields for FLS and Target…

• fields planted to FLS-susceptible varieties and with a history of frogeye leaf spot
• fields in continuous soybean production
• fields in short rotations between soybean crops
• fields with conservation tillage
• low-lying areas of fields

If you have fields that meet the above risk factors you should use a preventive fungicide application no sooner than R1. If you find FLS in R1 soybeans spray immediately with a FRAC Group 3 (DMI, triazole) fungicide as these fungicides have some curative activity. University pathologists in the U.S. have had the best results with Domark, Topguard, Lucento, Revytek, and Miravis Top when spraying after FLS is detected. Follow-up sprays may be needed if FLS continues to progress.

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 10^th.  But with peanuts so far behind I’d consider shifting that back to no sooner than July 15^th, 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

I’ve been getting questions about peanut in-furrow fungicides and nematicides lately. The primary question is what to use in-furrow since Proline availability is limited, but should be available for later plantings.

Let’s start with why in-furrow Proline was initially recommended for peanuts. In-furrow applications of Proline were found to reduce losses to CBR (Cylindrocladium black rot ) in the early 2000’s by Dr. Pat Phipps. While not as effective as the fumigant Vapam, growers used it because it was less expensive and much easier to apply than Vapam. This caused widespread use of Proline in-furrow in Virginia and North Carolina and became a standard practice to reduce losses to CBR. The early trials evaluating Proline in-furrow did not demonstrate activity on any other peanut disease in Virginia. Thus, Proline in-furrow was used specifically to reduce losses to CBR.

Fast forward to 2023. Due to past and continued breeding efforts towards CBR resistance in Virginia-type peanuts coupled with longer peanut rotations, CBR has become a disease of the past. We have not observed a single peanut sample in the Tidewater AREC Plant Diagnostic Lab where CBR was confirmed as causing disease on peanut since I started here back in 2014. I have not heard anyone mention problems with CBR in Virginia or North Carolina nor have I seen it in my peanut trials or grower fields. So why are some growers still using Proline in-furrow, especially since the disease it was meant to control is not a problem. Good question! I have not used Proline or any other in-furrow fungicide in my peanut trials for years with no issues.

So what’s the bottom line? To me, Proline in-furrow is an added expense that doesn’t provide measurable disease control in our area unless you’re growing Valencia peanuts or another type besides Virginia-type peanuts. Also, there is no replacement product currently labeled for peanut except Propulse which contains the active ingredients in Proline and Velum. I have had someone ask about using Provost Silver as an in-furrow replacement for Proline because it contains the active ingredient in Proline (prothioconazole), but Provost Silver is not labeled for use in-furrow and the tebuconazole component will cause delayed emergence and growth in seedling peanuts. What about Velum? Velum in-furrow is labeled for Aspergillus crown rot, early season leaf spot, early season southern stem rot (white mold), and nematodes. In Virginia, the utility of Velum in-furrow is primary against nematodes. In my opinion, the “must have” in-furrow products on peanuts across the board should be inoculants and thrips control insecticides. I don’t see dropping Proline in-furrow on peanuts causing any disease issues.

If you have questions about in-furrow fungicides in peanuts, please feel free to contact me by e-mail (dblangston@vt.edu) or by phone: office (757) 807-6536; cell (757) 870-8498. If you want to drop in, my address is 6321 Holland Rd., Suffolk, VA 23437.

Nematodes consistently rank as a top yield robber of soybeans. Please plan to join us virtually on December 5 from 1:00-3:00 PM for the Nematode in Atlantic Soybean Production Webinar. This webinar will include results from Soybean Cyst Nematode seed treatment trials, Root-Knot Nematode on-farm trials, emerging management strategies, and feature a panel discussion on needs to improve nematode management in the region. The webinar is free, but registration is needed for access to the zoom link. Registration information can be found athttps://www.pcsreg.com/2022-nematodes-in-atlantic-soybean-production-webinar.  Please email Alyssa Koehler akoehler@udel.edu with any questions.