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
We know that we aren’t the only ones, but we are monitoring corn earworm moths again in Virginia at multiple locations. Pheromone trap counts of 7 or more moths per week indicates that this pest is active on the farm and could potentially become a pest threat to the numerous crops that it attacks such as sweet corn, cotton, hemp, soybean, tomato, and many others. Female egg-laying moths are particularly attracted to flowering plants or plants with fruiting stages.
Corn earworm moth.
Trap catch for this week ending June 29 at several locations is as follows:
Townsend (Eastern Shore) – 4 moths
Cheriton (Eastern Shore) – 0
Machipongo (Eastern Shore) – 0
Nassawadox (Eastern Shore) – 0
Clover (Southside VA) – 66 moths
Blacksburg (southwest ridge and valley) – 2 moths
Thank you to Helene Doughty who is monitoring the traps on the Eastern Shore, Bill Tiver who is monitoring a trap in Clover, VA, and Brian Currin who is monitoring traps around Blacksburg. Moth catch was low on the Eastern Shore and in Blacksburg this week, but rather high at the Clover site; however, sweet corn is in reproductive stages on that farm and probably a very attractive location in southside, VA.
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.
Cereal leaf beetle, a pest of small grains, overwinters as an adult.
Cereal leaf beetle adult
When temperatures warm, adults migrate to small grains to lay eggs; eggs are yellow-orange in color, usually in the midvein of the leaf, and may be single or several eggs end-to-end.
Cereal leaf beetle eggs
I saw a few eggs at our research center field today (March 9), they were a bit darker (and stickier) than their normal color. A female may lay 50 eggs. Larvae have orange-yellow bodies with dark heads and legs, but often appear as shiny black due to the covering of mucus and fecal matter they have on their body (they look like small slugs).
Cereal leaf beetle larvae and characteristic skeletonized leaf feeding injury
Larval feeding strips leaves of phytosynthetic tissue and can cause reductions in grain quality and yield. A temperature-based model developed using Virginia and North Carolina data shows that peak egg lay occurs at approximately 182 degree-days (using January 1 as a biofix; a lower development threshold of 8℃, and an upper development threshold of 25℃). With our warm February 2023 temperatures, we hit an earlier-than-normal peak egg threshold in Suffolk, VA on March 3 (I used the Tidewater AREC WeatherSTEM as my temperature source). The larval peak follows the egg peak by an average of 17.5 days, which would be the third week of March for Suffolk. It is important to note that the model states that extremely hot or cold years may affect its accuracy. Dominic Reisig (Professor and Extension Specialist, North Carolina State University) posted that the Salisbury, NC egg peak was predicted to occur on March 5-11, but a cooler forecast may push back the larval peak to the last week of March. As of March 8, Warsaw, VA is at 123 degree-days for cereal leaf beetle and the Eastern Shore has accumulated 119 degree-days.
To scout for cereal leaf beetle, inspect 10 tillers (stems) in at least 10 different sites. If you are seeing mostly eggs, you should scout again in 5-7 days when some have hatched into small larvae. The eggs may be parasitized. Both Virginia and North Carolina recommend an economic threshold of 25 eggs + small larvae (total) per 100 tillers. At least half of that 25 should be larvae. An insecticide spray, if needed, should target the newly-hatched larvae. Please refer to pages 4-44 and 4-45 of the Virginia Cooperative Extension 2023 Field Crops Pest Management Guide for additional information and spray recommendations. Another useful resource is a Journal of Integrated Pest Management article by Philips et al. (2011), Fifty Years of Cereal Leaf Beetle in the U.S.: An Update on Its Biology, Management, and Current Research.
Everyone is gearing up and planning for potato planting to begin soon! With two primary insect pests of great economic importance: Colorado potato beetles and wireworms, growers are sometimes perplexed on what the best option may be or looking for that new product that will solve all their insect problems.
COLORADO POTATO BEETLES: No new products have been registered for Colorado potato beetle control for 2023. However, at-planting neonicotinoid insecticides are still working well in our area (thankfully!). Field trials at the ESAREC in 2021 comparing labeled at-planting insecticides yielded great results for Colorado potato beetle control, up to 56 DAP (Figure 1 and 2). Similar residual efficacy has been shown on commercial farms on the Shore as well based on previous assays from 2021.
Colorado potato beetle adult. Fig. 1. Results of at-planting insecticide efficacy trial conducted on potatoes in Painter, VA, 2021.Fig. 2. Yield of potato tubers from an at-planting insecticide efficacy trial conducted in Painter, VA 2021.
And for those pesky beetles infesting fields later in the season (likely from neighboring potato fields from the previous year) once the at-planting insecticide has worn off, there are still numerous options for foliar control (being mindful to rotate to a foliar insecticide in a different IRAC group) (Figure 3). A couple new insecticides with new mode of actions should be available later in 2023 or 2024, which have performed very well in our CPB efficacy trials; these include plinazolin a new Group 30 mode of action, and Calantha (a new RNAi insecticide that is highly specific to CPB and not toxic to any other organisms).
Fig. 3. Insecticides registered for use on Colorado potato beetle on potatoes in Virginia.
WIREWORMS:
Questions about wireworm control come back every year. With recurring problematic fields, growers are always in search of new options. Based on 15 years of research at the ESAREC, the combination of Regent (fipronil) with a neonicotinoid (thiamethoxam or imidacloprid) at planting still offers the best control for seedpiece protection. A new option is available in 2023 with a group 30 insecticide, broflanilide, currently marketed under the trade name Nurizma. We are looking forward to testing it as an at-planting insecticide in our potato field trials in the upcoming season. We are also interested in assessing the wireworm suppression ability of this same insecticide applied as a seed treatment to wheat cover crops. Research has shown that this can significantly reduce wireworm populations in a field for subsequent crops like potato.
More research work in the upcoming years will continue to focus on understanding the biology of this pest in its larval and adult stage as well as reduction of wireworm population in fields for potato production through seed treatments in rotational crops.
Wireworms collected from the Eastern Shore of Virginia.
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.
By Lorena Lopez, Alejandro Del Pozo, and Tom Kuhar.
We continue to see severe pickleworm infestations in squash and pumpkins grown in the Hampton Roads area (Table 1). Summer squash season is gone but beware of your pumpkins. Systemic insecticides are recommended to mitigate pickleworm infestations since contact insecticide cannot reach the larvae that burrow into fruits and flower buds (see the link below for insecticide recommendations). Pickleworm larvae can burrow into pumpkins after harvest as well when they are beautifully displayed in your porches or gardens.
Crop
Row
Fruits_with_holes
Undamaged_fruit
Percent_damaged
Zucchini
2
5
5
50
Zucchini
4
4
6
40
Pumpkin
1
11
4
73
Pumpkin
2
12
3
80
Table 1. Percentage of zucchini infested with pickleworms in the Hampton Roads AREC on Sep. 27, 2022
By Lorena Lopez, Alejandro Del Pozo, Helene Doughty, and Tom Kuhar
After pickleworms and melonworms showed up late in the summer season, we detected severe infestations (Table 1) in the Hampton Roads area and found both pests in the Eastern Shore AREC (Painter, VA) infesting summer squash and pumpkins. Beware of your pumpkins and examine your plants weekly for these pests which can be severely damaging and affect significantly your yield. In the links below you can find details on how to ID these pests and recommendations on what insecticides to use in case of infestation.
Crop
Row
Fruits_with_holes
Undamaged_fruit
Percent_damaged
Zucchini
1
6
4
60
Zucchini
2
5
5
50
Zucchini
3
5
5
50
Zucchini
4
9
1
90
Pumpkin
1
11
4
73
Table 1. Percentage of zucchini infested with pickleworms in the Hampton Roads AREC on Sep. 19, 2022
This week FAW adults were observed at 3 of 12 monitoring locations throughout the state. The West Central region (Montgomery county) had sites with up to 4 individuals per trap while more eastern regions of the state (Hampton Roads) observed up to 14 individuals per trap in Virginia Beach and Glen Allen, VA. See table for all locations and counts.
The soybean crop is rapidly moving along. Normally the R6 or late-seed filling stage will last about 3 weeks, although that time will shorten with late planting. Most of this year’s crop has reached that stage with the exception of late-maturing varieties planted double-crop after wheat harvest.
The crop has made only 50% of it’s yield at the beginning of this stage and about 75% of its yield 8 to 12 days into the stage. Only after the crop reaches physiological maturity is 95 to 100% of the yield been made. If stress such as we are having now occurs during this time, seed size will be small and some seed will abort in the pods.
The dry weather that we’ve recently experienced is speeding up development, aborting seed, and small seed size will likely occur. Areas that have received recent rainfall may not experience this. Unfortunately, yield may not be as good as they appear – the pod load will be deceiving in dry areas.
Aborted seed due to drought
There are still some late-season decisions that need to be made in some parts, such aa harvest aid timing or late-season insecticide application.
So when can you apply a harvest aid to control weeds or possibly speed up development? First you need to follow the label. Different harvest aids have different requirements. Many are not allowed/legal until R7. If you however select a harvest aid that can be applied in the late-R6 stage, I suggest waiting until at least half of the leaves on the plant have dropped and half of those remaining are turning yellow. This is only within a few days until R7; about 15 days after beginning R6. Most of the yield should have been made by this time. Any application before this time could affect yield.
What if you are experiencing insect defoliation? Both Mexican bean beetle and soybean looper are causing some problems in different parts of Virginia. First, is it worth treating for defoliating pests at this late stage? If you have not entered the R6 stage and are still at R5, then severe defoliation (>15%; >10% for late-planted, poor growth) could greatly impact yield. But what if you are in the R6 stage? This will depend on 1) presence of the pest and how much defoliation you have experienced; 2) how long before you are at a “safe” stage, where you’ve reached most of your yield potential; and 3) the amount of leaf area – the more the better.
Our Pest Management Guide thresholds indicate that we can tolerate up to 35% defoliation for soybean that contains fully-developed seeds (with good growth/high leaf area; less for late-planted, poor growth). But we also need to consider how long before we reach R7. If you are half-way through R6, then you are probably “safe” and don’t need to spray, depending on how fast the defoliation is occurring and the number of pests present.
However, if your are only a few days into R6, the decision is much harder. As you can see from the above diagram, we’ve only made 50 to 75% of our yield by this time. With excess leaf area (we have this in many parts of Virginia this year), you can tolerate a good bit of defoliation, even at this stage. The real questions are how long before I reach the “safe” stage and how fast is the insect pest defoliating the crop. As I stated earlier, the dry weather is speeding up maturity; so, time to maturity could be reduced by several days. The crop could be getting less valuable with time. If this is the case, I would not expect a benefit of an insecticide application. But what if the crop is not under stress? As an agronomist, I lean towards protecting crop yield. But, these questions can only be answered on a field by field basis. And you’ll need all the information that you can get, from various sources.
