Month: May 2023

Growers, Grafters, Researchers, and Extension Partner in Identifying Best Management Practices for Grafted Vegetable Plants – Watermelon in Ohio in 2023

Many growers know that grafting gives them access to much needed disease resistance – stronger resistance to some diseases than available in hybrids and more resistances than often found in them, too. Indeed, a quick scan of rootstock characteristics at http://www.vegetablegrafting.org/resources/rootstock-tables/ reveals that few commercial hybrid varieties of tomato or watermelon include some resistances found in rootstocks. However, the greater cost of grafted plants has many people asking how growers’ profits can be maximized when using them. Lowering costs and boosting yield and quality are key parts of the answer.

Best Management Practices (BMPs) are “how-to” guides used in commercial crop production. BMPs are developed over years of collaboration involving many people since they involve optimizing every aspect of individual production systems from site and variety selection through post-harvest handling, packaging, and delivery. Current vegetable BMPs are based on the use of nongrafted plants. However, grafted plants tend to be more vigorous than and different from nongrafted ones in other ways. More important, perhaps because of these differences, grower and researcher experience with grafted vegetable plants indicates that farm BMPs must be updated to lower the costs and maximize the grower profits associated with using grafted plants. Optimizing plant density (number of plants per acre based on in- and between-row spacing), and irrigation, fertility, and harvest management for many scion-rootstock combinations has become the focus of much on-farm and on-station research.

Four Ohio farms, The OSU North Central Agricultural Research Station (https://oardc.osu.edu/facility/north-central-agricultural-research-station), and OSUE will evaluate the effects of plant density using four scion-rootstock combinations in 2023. Drawing on previous work (e.g., https://u.osu.edu/vegnetnews/2021/08/21/grafted-watermelon-plants-under-what-conditions-and-practices-does-using-them-offer-the-best-return-on-investment/), plants provided by Tri-Hishtil of Mills River, NC (https://www.trihishtil.com/) will be set at a range of in- and between-row spacings affecting potential grower costs and, possibly, fruit maturation, yield, and/or quality. Within and across sites, the total plant population is expected to equal roughly 450 – 1,450 plants per acre in individual plots. The team is intrigued by the possibility that yield and quality will remain high in some treatments/plots although many fewer plants, rows, and various inputs will have been used.

We would like to hear from you if you have questions about making and/or using grafted vegetable plants or information on the topic. Please contact Matt Kleinhenz (kleinhenz.1@osu.edu; 330.263.3810).

Solar Development in Ohio

Here’s a chance to learn more about current issues and trends in solar development and solar leasing in Ohio! Register at go.osu.edu/solarwebinars. Recorded webinars will be available on the Farm Office website at https://farmoffice.osu.edu/our-library/energy-law.

DATES: May 23, 24, 25, 30 and 31

Solar Webinar Flyer

Striped Cucumber Beetles Appearing Soon at a Field Near YOU!

Jim Jasinski (Extension), Ashley Leach (Entomology)

It’s been cool and wet in most of Ohio slowing most planting schedules but cucurbit planting is poised to hit it’s stride toward the end of May through mid-June. This means growers need to be on the lookout for the primary early season pest of pumpkin, squash, melons, cucumbers and zucchini, the striped cucumber beetle.

Striped cucumber beetle adult.

These adult beetles are overwintering now but will begin actively searching for cucurbit seedlings to feed on, sometimes inflicting severe enough damage to outright kill plants. Recall that while seedlings can survive and outgrow minor beetle damage, it is key to avoid severe damage to seedlings in order to prevent bacterial wilt transmission while the plants are most susceptible, typically prior to the 3-4 leaf stage. Bacterial wilt infected plants will become symptomatic once there is high demand to translocate water from the roots to the shoots, such as the time of fruit enlargement. No treatments are available to reduce bacterial wilt once a plant is infected.

Bacterial wilt infected plant in foreground, healthy plant in background.

Scouting newly emerged cucurbit plantings every few days is essential to determine if enough beetles or damage is occurring to warrant treatment. Action thresholds vary from 0.5 – 1 beetle per plant for cotyledon and 1st leaf stage seedlings to 1-2 beetles per plant for 3-4 leaf stage seedlings. Scout about 50 plants in both edge and interior areas throughout the field, flipping over leaves and especially looking under cotyledons to accurately determine beetle pressure and damage.

Severely damage cotyledon by striped cucumber beetle feeding.

Foliar insecticide recommendations for all cucurbit crops can be found in the Midwest Vegetable Production Guide (https://mwveguide.org/uploads/pdfs/Cucurbit-Crops.pdf).

To prepare for the arrival of striped cucumber beetles, consider reviewing a short but detailed video of several management options (beetles/plant thresholds, systemic seed treatment, use of transplants and in-furrow application) posted to the OSU IPM YouTube channel (https://youtu.be/RSzTT_gbma4).

A quick word about using insecticides to manage early season beetle populations. Based on your farm history with damage from this pest, field size, time of direct seeding or transplanting, you may not experience peak beetle pressure and can manage this pest by frequently scouting seedlings and treating if over threshold, the old fashioned IPM method!

If you purchased systemic insecticide coated seed (FarMore FI 400) which is very effective at controlling beetles, as evidenced by the pile of dead cucumber beetles on and near the treated plant, be aware that trace residues will accumulate in the pollen and nectar. If foraging honey bees, bumble bees, squash bees and other pollinators collect these food resources they may not be outright killed but more subtle sub-lethal effects on brood such as reduced feeding, fewer wax cells constructed, fewer eggs laid and other effects might occur. So, decisions about pesticide selection, pest severity, timing and non-target impacts should be considered before use.

Dead cucumber beetles at base of systemic insecticide treated plant. Courtesy of Celeste Welty.

If using FarMore FI 400 treated seed to raise transplants, do not treat them again with a systemic insecticide product during field setting as this will increase the residues found in pollen and nectar. If applying systemic products in-furrow, using the lowest labeled rate will still provide great beetle control for 2-3 weeks.

Mustard Project to Help Pollinators  

Jim Jasinski (OSU Extension), Chia Lin & Reed Johnson (OSU Entomology), Hongmei Li-Byarlay (Central State University)

Brassica cover crops like mustard (Brassica juncea) and rapeseed (Brassica napus) can be a good fit in some production systems, providing a range of benefits such as soil health, soil biofumigation and pollinator health.

Blooming mustard crop.

Recently it was reported that the natural biocides (glucosinolate compounds) produced by mustard plants could mitigate infections of Nosema (a fungal parasite) in honey bee colonies.  If glucosinolates are present in mustard pollen, mustard blossoms may provide the dual benefits of food source and disease control for honey bees.

To test that hypothesis, a two-year multi-site research project led by Dr. Chia Lin was recently funded to look at the effects of spring (mid-April) and late summer (late July) planted mustard as a cover crop to provide abundant pollen to foraging bees in order to measure specific effects on colony health. Both lab and field studies will be used to identify how much mustard pollen is collected by the bees and beneficial aspects of the targeted mustard planting on reducing Nosema impact on honey bees and improving winter survival of bee colonies.  Stay tuned for updates on this project.

Mustard cover crop emerging from one of the research sites.

Mad about Maggots?

Have you visited your vegetable field lately and come back disappointed because you were met with wilted, drooping plants? You are not alone. Recently, we have had an uptick in reports of maggot damage in vegetable crops. The insect culprits in question are most likely either onion maggot, seedcorn maggot or cabbage maggot. These maggots are very similar, and even belong to the same fly genus, Delia. These cream-colored maggots are small (0.5-1.5 cm) and have between 3-5 generations per year. These fly species will overwinter as pupae in the soil and emerge as adult the following year to find suitable host plants. Maggot will feed on seedlings and either kill the plant before it can successfully mature or injure the plant, thus giving entry to soil pathogens (secondary infections). This past season, you may have noticed more damage from maggots than normal. And that’s not surprising; maggot damage is typically greater in cool, wet seasons and in fields with high organic soil types.

There are some differences between these species that may point to one being the cause over another. Onion maggots love alliums, and are most problematic in onion, garlic, and leek. Cabbage maggot has an affinity for brassica crops including cabbage, cauliflower, Brussel sprouts, and turnips. Seed corn maggots love just about everything and can be found in as many as 40 different plant hosts. Notable crop hosts for seed corn maggot include soybeans, corn, beans, peas, cucumber, melon, pepper, potato, and even onion. As a general rule, seedcorn maggots typically damage the seed, whereas onion/cabbage maggots often feed on seedling roots.

The bad news is that if you are facing maggot damage there is little you can do to “rescue” your planting. Your best bet is to wait it out and replant if possible. You can drench with Diazinon (Diazinon AG500), but this product won’t ultimately save you from the damage that has already been afflicted. If you decide to use this product, make sure you use enough water. Diazinon doesn’t move easily through the soil and is best applied with adequate water.

Avoid “chasing” adult flies. You may see adult flies (figure 1) in your field but using foliar insecticides to kill adult flies is not an effective option for any species. Keep in mind the damage is in the soil, so make sure you target your management decisions to strategies that will protect the below-ground tissues of the plant (I.e., seed treatments or in-furrow applications at planting/transplanting).

If you are dealing with maggot damage on your farm, consider some of the options below.

  1. Prevention is key. If you know you have a history of either seed corn maggot or onion maggot, make sure you take action by preventing an infestation before it starts.
    • Rotate your crop. Flies will show up when they know food is available. So do your best to confuse the flies by rotating your crops, especially alliums and brassicas. If you want to limit future infestations, consider planting a non-host crop to decrease the likelihood of subsequent maggot problems. If you are rotating your crop to a non-host, make sure you rogue out any volunteers from the previous year. (Maggots love volunteers!)
    • Use a seed treatment (Table 1). Insecticide treated seed is one of the most effective tactics to manage maggot populations. A number of efficacious products are available including thiamethoxam+ spinosad (FarMore FI500), cyromazine (TRIGARD), and clothianidin and imidacloprid (SEPRESTO) for many vegetable seeds (table 1). Rotate products between years so you are not exposing multiple generations to the same active ingredient. For example, if you are using FarMore in year 1, rotate to a different seed treatment like Trigard or Sepresto in year 2. WHY DOES THIS MATTER? Reports from the Northeast and MidAtlantic suggest that some maggot populations may become resistant to these seed treatments.
      Table 1: seed treatment options to manage  maggot infestations in vegetables. Please note that efficacy of these products may differ based on maggot infestation and/or soil type.
      Product OMRI listed? Active ingredient Relative control of maggot IRAC codes
      FarMore FI500 No. thiamethoxam+ spinosad Excellent. 4A, 5
      Trigard OMC No. cyromazine Excellent. 17
      Sepresto 75 WS No. clothianidin+ imidacloprid Good. 4A, 4A
      Regard SC Yes. spinosad Excellent/Good. 5
  2. Exclude flies from the crop. One viable management approach is to keep female flies from finding your crop. You can isolate your crop either in space (row cover) or time (degree day modeling).
    • Consider using row covering over your susceptible crops to stop adult oviposition (egg-laying). Multiple studies have found that this is a highly effective method at limiting damage.
    • Avoid maggot damage altogether by planting later in the season to bypass peak infestation. Maggots have predictable phenological patterns, and you can use degree day models to accurately predict times in the season when maggot risk is high. The first peak of seedcorn maggot occurs earliest in the season when 200 degree days has been accumulated, followed by cabbage maggot (250 degree days) and then onion maggot (250-300 degree days).
  3. Monitor, monitor, monitor. While there is little you can do to manage maggot infestations within the immediate growing season, it’s important to identify problem areas so you can plan accordingly for the following year.
    • The best way to tell if you have Delia maggots on your farm is to scout early and often. Fields with poor plant emergence or wilted seedlings (figure 1, video) should be inspected for maggot damage. Make sure you cull any infested plants.

Successful Production Begins with the Best Varieties: An Example from Potato Breeding

If you grow potatoes for profit, chances are you rely on varieties developed by a university-USDA-industry team dedicated to improving your success by improving the varieties available to you. This article outlines aspects of that process and The OSU’s participation in it in 2023, as in more than fifty previous years.

The overwhelming majority of potato varieties used in Ohio and the U.S. are developed by university- and USDA-based programs and teams. These teams are led by breeders-geneticists and include plant pathologists, entomologists, food scientists, horticulturalists, and others working closely with growers, grower organizations, processors, retailers, seed certification programs, and members of industry and government. The small number of teams in the U.S. are based in major production regions, e.g., Northwest North-central, and East, allowing them to develop varieties best suited to these regions. The OSU has cooperated with the Eastern team with breeding programs in Maine, New York, and North Carolina and partners in other states for more than fifty years (see https://neproject.medius.re/ and potato reports at https://u.osu.edu/vegprolab/technical-reports/). The OSU also collaborated with the North-central team with breeding programs in Michigan, Wisconsin, Minnesota, and North Dakota for more than forty years. Regardless of team, working from industry and consumer input, our goal has been to improve marketable yield regardless of production constraints (e.g., disease, nematode, abiotic stress), tuber quality (including sensory properties and nutritional value), crop use of natural resources (e.g., water, fertilizer) and other characteristics. Efforts completed here continue to benefit growers, processors, retailers, chefs, consumers, and others in Ohio and throughout the Eastern U.S.

Potatoes are clonally propagated – i.e., tubers are clones of their mother plant. This means that increasing the availability of seed for a new superior variety can be more straightforward than in crops requiring true botanical seed. However, in its early stages, potato breeding requires creating and evaluating experimental lines resulting from ‘hybridizing’ crosses, e.g., as in tomato variety development. Many crosses are unproductive while others result in experimental lines worthy of additional evaluation under a wide range of conditions. That is when a network of collaborating evaluators operating in various environments where the experimental line/new variety could be grown commercially becomes essential.

In 2023, The OSU will evaluate 126 experimental selections against 12 standard varieties. As before, selections from the University of Maine, Cornell University, USDA-ARS in Maine, and North Carolina State University will be featured and our evaluation process will focus on the interests of growers, processors, retailers, chefs, and consumers. Plots are located at the OSU-Wooster/OARDC and can be viewed anytime. If possible, please contact Matt Kleinhenz ahead of time so he can welcome you properly and help you benefit fully from the tour (kleinhenz.1@osu.edu, 330.263.3810). Also, seed is available to growers who wish to evaluate experimental selections on their farms.

A subset of the information that will be collected for each experimental line through November-2023 is listed below.

Before Harvest
1. Percent stand (# seed pieces planted versus number of plants established)
2. Plant maturity
3. Tuber bulking period
After Harvest
4. Total yield
5. Percent tubers greater and less than 2 inch in diameter
6. Percent of tubers that are misshapen or have a similar market defect
7. Basic tuber characteristics (9 options for each of the following six characteristics – 531,441 possible combinations!): a) skin color, b) skin texture, c) shape, d) flesh color, e) eye depth, and f) uniformity
8. Tuber internal quality (incidence of defects)
9. Specific gravity
10. Chip quality (color, blister), including as chipped directly after harvest or storage (with or without reconditioning). Chip-stock production in Ohio is mainly for situations in which crops are chipped directly after harvest with no storage period.

Regardless of market, on all but a small set of operations, potato vines are removed before harvest either mechanically (quickly) or chemically (slowly). How vines are removed is important to growers and all members of the potato value chain. They all want tubers well suited to a specific end use; however, some varieties may respond less desirably to quick, mechanical vine killing, especially if vines have not died naturally or are not actively senescing. Applying a desiccant that kills the vines slowly and promotes tuber skin set and stolon detachment is most common. However, some growers may choose or be required to harvest crops “green,” when vines have not died or have been chopped very recently, a typical approach to mechanical vine killing. Importantly, vine killing methodology can affect the condition of the tubers at harvest and after, during processing, storage, shipment, and preparation. Killing vines quickly and harvesting soon after can influence various tuber properties including: a) stolon attachment, b) skin integrity/scuffing, c) physical damage, d) relative abundance of starch versus reducing sugars, e) incidence of bruises, and f) storability. Buyer and grower tolerances for these issues can be low so identifying lines capable of being harvested “green” and used effectively can be important. Of course, some consumers prefer small “new” tubers with very thin skins so these crops must be handled carefully. Similarly, growers and processors are also keen to discover the optimal storage conditions for experimental lines and new varieties and the extent to which their tubers must be “reconditioned” before use as referenced in https://www.potatogrower.com/2019/03/top-5-factors-to-successful. Through the years, once popular processing varieties were displaced by new ones with less stringent storage-reconditioning requirements, a discovery made during collaborative testing by variety development teams and industry.

As always, the 126 experimental lines will also be evaluated for their resistances to multiple diseases, nematodes, and insect pests by other team members in Maine, New York, Pennsylvania, Virginia, North Carolina, and Florida. Cooking and consumer evaluation tests will be completed.

Information that will be collected before and after harvest is key because plant and tuber characteristics and yield strongly help determine the main end use and market for which a variety is best suited: a) general fresh market, b) specialty fresh market, c) processing (e.g., chip), or d) fresh-processing dual purpose. Of course, this also means the same variety profile also determines which farms and farmers will benefit most from using a new variety. Production for chip and direct-retail markets has increased in Ohio in recent years.

As shown earlier (see https://u.osu.edu/vegnetnews/2023/03/11/how-will-your-yield-and-efficiency-increase-this-season/), U.S. potato yields have climbed steadily for more than a century. This increase is due to better varieties and crop management. Regardless of your market, if potatoes are part of your business, it can be essential to watch for and test new varieties since they provide the greatest reward for your high-level skill as a grower. As much as possible, take advantage of that skill by using superior varieties instead of relying on it to overcome weaknesses of inferior ones. Future related articles will provide information specific to obtaining seed for new or “alternative” varieties that may benefit your business.