Poison hemlock and Canada thistle are making unwelcome appearances across Ohio, and that raises the need to talk about Ohio’s noxious weeds law. The law provides mechanisms for dealing with noxious weeds—those weeds that can cause harm to humans, animals, and ecosystems. Location matters when we talk about noxious weeds. That’s because Ohio law provides different procedures for dealing with noxious weeds depending upon where we find the weeds. The law addresses managing the weeds on Ohio’s noxious weeds list in these four locations:
- Along roadways and railroads
- Along partition fence rows
- On private land beyond the fence row
- On parklands
Insects continue to be the main headline in the vegetable crops in our area. Of greatest concern is the cucumber beetle. The populations continue to increase in number and the efficacy of seed treatments or in-furrow applied insecticide starts to decline 4-6 weeks after the seed germinates or after the insecticide is applied. This means that more of the beetles are feeding without being affected by the insecticide. Be sure to scout cucurbit crops frequently and carefully to get accurate counts of the beetles. The thresholds for cucumber beetles are as follows: Cotyledon stage – .5 beetles per plant, 2-4 leaf stage – 1 beetle per plant, greater than 4 leaves – 3 beetles per plant. Limiting the amount of feeding that cucumber beetles do will also limit the amount of bacterial wilt occurring in these plantings. Do be cognizant of the plants that are in bloom and limit your spraying to a time when it will be least impactful on the pollinators.
Other insects that were spotted this week include Colorado Potato Beetle larvae and imported cabbage worms. Both of these pests can cause significant damage in their respective crops when left unchecked. Flea beetles also continue to feed on plantings of cole crops, preferring young transplants versus older, more established plantings, although both should be inspected for beetles.
Sweet corn plantings are growing quickly and some plantings that were done into plastic mulch and covered this spring already have a few tassels poking out. Overall, there has been no major concerns in the sweet corn plantings so far, however, do your best to keep up on weed control. Weeds such as bindweed, thistle, and ragweed can not only compete for resources, but can also make harvest difficult and may serve as refuge locations for insect pests to retreat to.
Small Fruit and Orchards
We are beginning to enter a critical period for managing diseases in grapes. This period, which extends from immediate pre-bloom through four to five weeks post bloom, is a critical time to control fruit infections by the pathogens which cause black rot, powdery mildew, and downy mildew. According to the 2021-2022 Midwest Fruit Pest Management Guide, the fruit of the most commonly planted varieties becomes resistant to infection by these diseases by four to five weeks after bloom.
In strawberry plantings we are seeing a lot of green fruit and in some locations, harvest is beginning to ramp up. Overall, there have been very few concerns in the
strawberries to this point, with just a few slugs here and there and a spotting of powdery mildew on a few plants. Powdery mildew is managed by spraying either pre-bloom or during the early bloom through bloom stage.
Other small fruit like blueberries and brambles look to have a heavy fruit set this year. Blueberries are beginning to get some color to them, and the blackberry and raspberries are either in bloom or in fruit development.
In apple and peach orchards, the fruit are noticeably starting to increase in size. We are finding some aphids in apple trees, feeding on the leaves and new shoots. In peaches, we did find a few instances of powdery mildew affecting the fruit. Trap counts for OFM and CM were under threshold in all of our traps this week. The counts are down after last week with several orchards above threshold for CM and OFM counts.
February 4, 2021
12 pm EST, 9 am PST
This 1-hour long Zoom webinar, is meant for growers, and for people who assist them–especially pest management advisors and pesticide applicators. The event will host top-notch experts in the fields of herbicide science, plant pathology, atmospheric sciences and agricultural regulation. Register for free at: https://www.eventbrite.com/e/137078903691
This webinar will deal with pesticide application in agriculture, from the following perspectives:
- Damages to crops, due to pesticide and herbicide drift from neighboring fields.
- Inefficiency in pesticide application, and ways to correct it.
- Pesticide drift liability: perspectives and lessons to recipients and to sources;
- growers and pesticide applicators.
- Meteorological factors affecting pesticide application, and localized weather forecasting.
List of speakers:
- Prof. Doug Doohan (Herbicide Science), Department of Horticulture and Crop Science, Ohio State University.
- Prof. Dorita Edelstein (Atmospheric Science), Institute of Earth Sciences, The Hebrew University of Jerusalem and the Israel Institute for Biological Research.
- John Fentis, Esq. (Law), Environmental Director, California District Attorneys Association.
- Moderator: Dr. Nadav Nitzan, Head of Plant Pathology, Valley of Springs Research Center, Israel (formerly of the Department of Plant Pathology, Washington State University).
Register for free here: https://www.eventbrite.com/e/137078903691
If you are a vegetable grower in Ohio, the Midwest Vegetable Production Guide, is an essential resource to keep on top of the latest fertility, horticultural management, and pesticide recommendations for your operation. Each year the guide is edited and updated by specialist’s in eight states to bring you the most current information possible at the time of printing.
What’s new to the guide in 2020? Within the 262 spiral bound pages there is an updated Organic Production section plus updated sections on disease, weed and insect management on 45+ vegetable crops, from Asian vegetables to Zucchini.
The MVPG is also more mobile friendly now with an improved interface designed to get your crop production question addressed quickly. Enter your crop and pest information and receive cultural and pesticide recommendations matching your request. Try it out on your computer, tablet or smart phone at https://mwveguide.org. The site will default to the new interactive mobile friendly interface but if you want to access individual pdf chapters of the guide, click on the drop down and select “Production Guide.”
To get a traditional hard copy of the guide, contact your local Extension office and they can order a copy from main campus. Cost will be around $15.
MVPG cover for 2020.
If you want to order a guide online through the new Extension publications website, here is the link https://extensionpubs.osu.edu/2020-midwest-vegetable-production-guide-for-commercial-growers/. If you order the guide online and have it mailed to your house, it will cost $21.25 plus shipping.
Be sure to purchase your guide soon, there are only 90 copies left in inventory at OSU! Best of luck for a productive season!
On July 5th I posted an article acknowledging the difficult spring and early summer planting conditions most Ohio growers faced, and asked to let us (OSU specialists and Extension educators) know what kind of issues you were experiencing. Once these issues were identified, I began researching possible solutions in order to help growers salvage as much of the season and market as possible. Attached at the end of the article is a PDF with my responses to your questions.
I wanted to thank the 36 growers farming just over 500 acres who took time to respond to the survey. In general, most growers were delayed 2-4 weeks but had a crop in the ground now. The biggest concern besides the ability the control the weather, was that OSU specialists continue to post current information about crop management, pest management, and markets. Several articles along those lines have recently been posted to the VegNet Newletter and we will continue to do so, but if there is a specific topic that has not been addressed, please reach out and contact that specialist directly. Below is a list of OSU specialists and Extension educators with their contact information.
Best of luck to you for better weather this summer and a fair harvest this fall.
Specialist Area Contact
Doug Doohan Weeds email@example.com
Celeste Welty Insects firstname.lastname@example.org
Sally Miller Diseases email@example.com
Jim Jasinski IPM/Insects firstname.lastname@example.org
Brad Bergefurd Horticulture email@example.com
Matt Kleinhenz Horticulture firstname.lastname@example.org
Steve Culman Fertility email@example.com
In case you are not aware, we are having a Pumpkin Field Day on Aug. 22 at the Western Ag Research Station. Read more about it here https://u.osu.edu/vegnetnews/2019/07/25/pumpkin-field-day/
Ah spring! The war against weeds begins anew. The first major skirmish of the growing season should happen before planting. The stale seed bed technique is an often over-looked practice that can be used before planting. It works by first encouraging weeds to sprout and then killing them when they are young and most vulnerable. For organic growers, a stale seed bed can replace the effects of a pre-emergence herbicide. And when used properly, it can contribute to both short-term and long-term weed management.
Weed control can be handled with short-term or long-term approaches. Short-term management focuses on controlling weeds during the first part of crop growth when weeds are more likely to affect crop yields. Long-term weed management, however, works all season-long to deplete weed seeds from the seedbank (the reservoir of viable weed seeds in the soil). Whichever approach you take, using a stale seed bed is a great cultural weed control technique.
To use the stale seed bed most effectively, start several weeks before planting. An initial cultivation kills any emerged weeds that have overwintered. It also brings weed seeds to the surface where exposure to light and oxygen stimulate germination. Depending on the weather and types of seeds present in the soil, weeds may sprout up overnight or over a few weeks. When weeds have germinated and are still small and young, they are easy to kill with a second light cultivation. This process is then repeated as needed and as time allows. As few as three cycles of light/ shallow tillage can reduce the number of subsequent weeds noticeably. For fields and gardens with very heavy weed infestations more cycles of repeated tillage over a few years will be needed. Using a stale seed bed may push back your planting date; but in the absence of weed competition, the crop will have more access to water and sunlight and be able to make up for lost time.
Keys to Success
- Do not allow emerged seedlings to grow large. It is best to till lightly just as the first seedlings are emerging as this and the earlier ‘white thread’ stage are the most susceptible to desiccation. The more time new weeds have to develop roots, the harder they become to kill with a shallow cultivation.
- Keep the cultivation shallow to avoid bringing new weed seeds to the surface. The implement used to stir the soil should not go deeper than 2 inches with most of the stirring in the top inch.
- The technique is dependent upon having adequate soil moisture. Under drought conditions preparation of a stale seedbed may require irrigation to stimulate weed seed germination.
- Deeper initial tillage can be used to bury an existing weed problem. Tillage, especially when done with a disc or a power tiller, distributes the previous year’s weed seeds throughout the top 6 inches or so of soil. In contrast, an inversion tillage that turns sod upside down will place last year’s seeds 6 inches or so under the surface. From there they are unlikely to emerge unless further discing or lighter tillage moves them closer to the surface. Used skillfully, a deep inversion plowing followed by stale seed bed can put a serious surface weed problem out-of-sight and out-of-mind, at least until the next time the field is plowed deeply.
Stale Seedbed is most effective when it is part of a zero weed threshold system.
The common short-term approach to managing weeds, (weed scientists usually call this the “critical period approach”) is to control weeds aggressively during the first 4-6 weeks after the crop is planted. This 4-6-week period is the critical period during which crops stands are established and yield is secured. Afterwards weeds are of less threat to production; therefore, many farmers scale back control efforts. However, weeds that grow before and after the critical period are still a problem. If allowed to flower and set seed, they will be planting a future crop of weed problems. A long-term approach to weed management, called zero weed seed threshold, requires constant diligence and removal of all weeds before they produce seeds–even after harvest. Research indicates that 3-4 years of using this approach will result in a field with relatively few weeds, provided weed seeds are not introduced from without the field (in seed, irrigation water, on equipment, etc.).
Both short-term and long-term approaches have benefits and drawbacks, many of which depend on a farmer’s individual goals, crops, and available resources. A new online tool from Ohio State allows farmers to think through various weed control approaches in the context of their own individual situations. For those looking to make changes to their weed management, the Organic Weed Decision Making Tool, shows pros and cons of various strategies over time and gives steps to implementing new tactics. Learn more at go.osu.edu/eco-weed-mngt.
Cover Crops are a valuable tool in the toolbox of the backyard grower, community gardener and urban farmer. I planted a mix of cover crop species last fall in my community garden plot to keep the soil alive over the winter, prevent erosion and increase soil organic matter.
This species mix, especially the winter rye component, can be challenging to manage in the spring depending on when the soil is worked. The winter rye will die from mowing or crimping when it is going to seed and nearing maturity, but when tilled young, some of the grass will continue to grow.
The majority of my plot will be used for summer vegetables. I do not want to leave the ground bare until that point as the cover crops will continue to grow in spaces and weeds will fill in the rest. I would also lose organic matter and fertility from spring rains.
I rototilled over half of the plot to create a seed bed about 10 days after initial tillage. This will kill most of the remaining over-wintered cover crops and created a seed bed for planting. There is a loss of organic matter from tillage, but I did not have the option to drill in the seed.
I followed up with a planting of Buckwheat. Buckwheat is a versatile cover crop that tolerates poor soils, rapidly germinates, weed suppresses, attracts pollinators and when mowed, will rapidly break down prior to the next planted crop.
I will let the Buckwheat grow until mid-May. Then I will mow the space which will kill both the cover crop and any annual weed that germinates within the Buckwheat planting. It will also weaken any perennial weed that is growing. I will let the residue decompose for a few days and then till and apply plasti-culture mulch in the pathways prior to summer vegetable planting.
A few weeks ago, in Drift 101, I suggested that farmers should be cautious before concluding that sick crops are a result of herbicide drift from neighboring fields. Symptoms attributed to drift may be caused by other factors. Nutrient deficiencies may cause chlorosis (yellowing) and necrosis (tissue death), symptoms easily misinterpreted as resulting from herbicide exposure (https://vegnet.osu.edu/sites/vegnet/files/imce/newsletters/VegNet/5-31-16%20VegNet%20Vol%2023%20Issue%207myedits.pdf).
The herbicides 2,4-D and dicamba invariably cause distorted growth of foliage (Figure 1), but so can various environmental pollutants especially when those are concentrated in the greenhouse (Figure 2).
Likewise flood conditions, during which root systems are completed saturated with water for prolonged periods, are known to induce leaf twisting and formation of adventitious roots (Figure 3), symptoms associated with exposure to 2,4-D (Figures 1 & 4).
Even when herbicides are the cause, symptoms can occasionally be misleading and point incorrectly to a nearby field. Consider the case of glyphosate, still the most commonly used herbicide in the Midwest. Glyphosate is quickly absorbed by crop leaves and translocated to growing points. On most crops glyphosate damage becomes obvious 4 or more days after drift because new growth is chlorotic. On tomato, chlorosis most often appears as bands across the base of the leaflets (Figure 5). However in a small number of drift events, chlorosis may not appear at all; instead glyphosate induces leaf and petiole curling and twisting, symptoms reminiscent of 2,4-D or other synthetic-auxin herbicides.
Soil residues of environmentally persistent herbicides used in previous growing seasons must also be taken into account. Trace amounts of herbicides in the ALS and AHAS families can cause symptoms similar to those caused by 2,4-D and dicamba. Imazethapyr (Pursuit) is an AHAS herbicide used on soybean that controls weeds at low doses of 3-6 oz/Acre. In our lab, tomato flowering was sensitive to doses of the herbicide equivalent to 1/1000th of the field dose. This finding indicates that soil residues of imazethapyr applied two or more years before planting may still be sufficient to injure field grown tomato, as may drift of the herbicide from a nearby or not-so-nearby application.
Many more similar examples could be provided; hopefully, the take home message is that diagnosing crop injury symptoms is a complicated matter that must take several factors into consideration and can easily lead to mistakes being made. Tread cautiously.
We are under two weeks until the annual Pumpkin Field day on Thursday, August 17th, from 6-8PM at the Western Ag Research Station in South Charleston.
This year’s field day will offer beginning and experienced growers valuable research updates regarding disease management, insect management, weed control, and showcase some new pumpkin and winter squash varieties. Celeste Welty (entomology), Claudio Vrisman (plant pathology), Bryan Reeb (weed control), and Jim Jasinski (IPM Program and emcee) will be on hand to share their knowledge and answer your questions. There be presentations on how to identify and control weeds, insects, and diseases on this crop.
The field day will feature some traditional and new projects on the wagon tour, including a seven-treatment powdery mildew fungicide demonstration trial, a powdery mildew drip irrigation trial, a pumpkin variety trial with 20 hybrids ranging from small to large fruit, and a winter squash variety trial with 11 entries. This season has been marked by periods of heavy rain and cooler than average temperatures, resulting in seven hybrids that are a little behind schedule in terms of growth, having yet to produce any fruit. I anticipate by the field day they will have produced some fruit for you to see, although it may not be mature.
After the formal presentations, attendees will be encouraged to walk around the plots and interact with the specialists and other growers.
There is a fee of $5 per person; refreshments and handouts will be provided.
Pre-registration is requested by August 15th at www.surveymonkey.com/r/pumpkin17.
Here is the rough agenda for the field day:
5:30 Begin check in
6:00 Welcome, introductions, outline of field day
6:05 Board wagons and head to the plots
6:10 Orientation to plots, begin presentations
7:10 End formal presentations, begin plot walks
7:55 Board wagons, complete evaluations
8:00 Field day ends, travel safe!
See the preliminary flyer below for a few more details. Looking forward to seeing you there. Contact Jim Jasinski (firstname.lastname@example.org) or 937-462-8016 for more information.