All/multiple crops:
Please note the date change for the sweet corn and pumpkin IPM twilight meeting. It will be held on Wednesday, Aug. 23rd. For full details please visit https://enych.cce.cornell.edu/event.php?id=1802
Just some food for thought: The question about foliar feeding vegetables comes up all the time. Is there value in foliar feeding? In times of stress, like drought or the opposite with too much rain, yes foliar feeding may have some benefits. How does it benefit? The benefit comes in the form of the plant being able to recover faster when times return to normalcy (if there is such a thing anymore). However, if you plan on trying to feed all the nutrition a plant needs through foliar feeding, that is nearly impossible – leaves are meant to produce energy for plant, not absorb nutrients – that is the roots’ job. You still need to make sure the fertility in the soil is optimum for the roots to do their job and do it well. You might be able to feed a couple of pounds of nutrients through the foliage, but the bulk still needs to be taken up by the roots. The exception to that rule might be if there is a micronutrient deficiency such as boron, manganese etc. Since many times these are only needed in small quantities (1-3 pounds per acre), they can be addressed by foliar feeding. See the article from Dr. Gordon Johnson for more information on best practices for foliar feeding.
Alliums:
Tip burn in onions is a common sight right now. It is critical to identify the cause of tip burn to inform management decisions. Tip burn is expected in onions reaching maturity as the bulb pulls nutrients out of the leaf tissue to size up. However, excessive and premature tip burn can be caused by poor root function (saturated soils and/or root rots like pink root and pythium), Stemphylium leaf blight (tips often have a “dirty” brownish appearance where the fungal pathogen is sporulating), or spray injury (some bactericides with hydrogen peroxide and peracetic acid strip the waxy cuticle from the leaf and can lead to phytotoxicity when combined with oil-based pesticides and products containing metals like zinc and copper).
Onion bulbs continue to increase in size after the foliage lodges, or flops, and the neck begins to contract. Onions should be allowed to lodge naturally before harvest and curing for best storage potential.
Brassicas:
Flea beetles are active again in Eastern NY. This fact sheet has useful information on flea beetle life cycle and cultural control options. There are multiple labeled pyrethroid formulations that are effective for knocking down flea beetle populations, but products like Exirel (cyantraniliprole, IRAC group 28) have longer residual activity and can help reduce damage from reinfestation. Organic growers not using insect exclusion netting can use Entrust (spinosad, IRAC group 5) to reduce damage. It is generally recommended that a spreader-sticker be used when applying insecticides to waxy crops like brassicas, but always be sure to consult the label for adjuvant requirements.
Chenopods (Beets, Chard, Spinach):
Nothing new this week
Cucurbits:
Powdery Mildew Control Recommendations for 2023
Many of you know the frustration of trying to control Cucurbit Powdery Mildew due to its ability to develop resistance to many of the fungicides that are labeled. When using fungicides, it is important that you spend the time to review which FRAC (Fungicide Resistance Action Committee) Group (or family) each fungicide has been assigned too. This is important because it allows you to know which fungicides have the same of similar modes of action. It has become even more important because of the many pre-mixes of materials that are on the market that may contain several different FRAC Groups. These groups assist us in rotating the different modes of action and hopefully reduce the ability of the pathogen to gain resistance.
Every year we try to give you the breakdown of what’s working and what’s not according to what our recently retired Plant Pathologist, Dr. Meg McGrath, found during her trial work the previous season. Before Meg left, these are the fungicides and the FRAC Groups they belong to, that she found to still be working: Vivando (metrafenone, Group 50), Prolivo (pyrilfenone, Group 50), Aprovia Top (difenoconazole Group 3 + benovindiflupyr Group 7), Proline (prothiconazole, Group 3) and Miravis Prime (fludioxonil, Group 12 + pydiflumetofen, Group 7). Rates, use limits, REI, PHI’s etc. can be found at this link: 2023 Cucurbit Powdery Mildew Fungicide Table
Potential spray programs could look like:
Week 1 Vivando plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 2 Vivando plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 3 Aprovia Top plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 4 Aprovia Top a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 5 Vivando plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Another program could be:
Week 1 Proline plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 2 Vivando plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 3 Proline plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 4 Vivando plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 5 Procure plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Week 6 Vivando plus a protectant (chlorothalonil, sulfur, mineral oil or biopesticide)
Dr. McGrath also said in her final presentation to us in February of 2023, you could also use one application of leftover Quintec (quinoxyfen, Group 13) or Torino (cyflufenamid, Group U6) that you may have. However, Gatten (flutianil, Group U6) has not proven to be very effective in trials. However, these fungicides have had a high level of resistance the last 2 year’s in her trial work.
Organically, sulfur alone or Stargus + Regalia alternated with sulfur provided some control as did Theia alternated with sulfur.
More information on Dr. McGrath’s research not just on Powdery Mildew, but on Downy and other diseases of cucurbits can be found by visiting: https://blogs.cornell.edu/livegpath/research/cucurbit-powdery-mildew-research/
Plecotosporium blight in areas with lots of rain has really become an issue – look for sunken, diamond shaped lesions with a white center and tan borders on the undersides of the leaves on the veins, petioles or even the vines themselves. Several of the produces that control Powdery Mildew will also help control Plectosporium including Aprovia Top and Bravo (chlorothalonil).
Downy Mildew is showing up in more cucumber plantings in the Mid-Hudson Valley and Northern New York. Growers should continue to protect their cucumber and melon plantings with regular fungicide applications. Growers in all parts of the region should remain on a preventative spray schedule since spores can move readily in storms. Disk in fields that you are no longer applying fungicides or harvesting as they can serve as a source of disease inoculum for successive plantings. Management information for both organic and conventional production can be found here.
Nightshades:
Late blight has now been confirmed in Yates County, NY and Mauricie, QC. Maintain a tight preventative spray schedule and scout for late blight symptoms regularly so you can switch to late blight specific products if needed.
Early blight is quite prevalent in many tomato plantings now that fruit is sized and starting to ripen. Early blight lesions usually start on the lower portion of the plant and work it’s way upward – lesions start out as small blackish brown spots and enlarge with a target board appearance. There are quite a few fungicides labeled including Aprovia Top (Difenoconazole + benovindiflupyr – a FRAC Group of 3 + 7) and Switch (cyprodinil + fludiozonil – FRAC Group 9 + 12). Many of the products labeled are pre-mixes of different FRAC Groups so please pay attention to this when rotating products. Also remember to include a protectant like chlorothalonil.
Bacterial leaf spot on peppers continues to be a problem in areas that have had lots of rain the past couple of weeks. Continue to maintain copper applications to prevent fruit infection and defoliation. If plants lose too much foliage, not only will they not yield, any fruit that is there will be much more susceptible to sun scalding.
Colorado potato beetles continue to cause damage to eggplant crops in the Hudson Valley. Recently hatched larvae are the easiest to manage with insecticides. Be aware of the pre-harvest interval (PHI) of insecticides labeled for use on eggplant for managing CPBs; many labeled pyrethroids have a 7 day PHI, whereas products like Sivanto Prime (flupyradifurone, IRAC group 4D) and Exirel (cyantraniliprole, IRAC group 28) have a 1 day PHI and longer residual activity. Organic growers may have some success with Entrust (spinosad, IRAC group 5) at 6 fl oz/acre, but spinosyn-resistant CPB populations have been documented in the Northeast and anecdotal evidence suggests some CPB populations in Eastern NY may be becoming insensitive to Entrust. Please contact one of the specialists if you are observing decreased efficacy from Entrust in managing CPBs on your farm.
Corn:
Corn earworm (CEW) trap counts remain low, but damage from feeding appears to be widespread. We recommend scouting corn to determine whether spray is necessary.
Fall Armyworm (FAW) trap catches have been over 400 in parts of Eastern New York.
Miscellaneous:
Just a quick reminder about when we talk about fungicides and FRAC Groups – this stands for Fungicide Resistance Action Committee which helps evaluate fungicide products and ways to reduce fungicide resistance. Knowing FRAC Groups is helpful when looking at all of the different fungicides that are available and how to make sense of what to rotate through during the season to slow the development of resistance. They are also helpful in that they allow us to keep the fungicides that work the best around longer. So, when you look at any fungicide label, look for the FRAC Group number on the front cover of the label to help you rotate your fungicides!