Responses to Pumpkin/Squash/Melon Grower Stress Survey

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                        doohan.1@osu.edu

Celeste Welty              Insects                         welty.1@osu.edu

Sally Miller                  Diseases                      miller.769@osu.edu

Jim Jasinski                   IPM/Insects                  jasinski.4@osu.edu

Brad Bergefurd             Horticulture                  bergefurd.1@osu.edu

Matt Kleinhenz             Horticulture                  kleinhenz.1@osu.edu

Steve Culman                Fertility                         culman.2@osu.edu

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 http://u.osu.edu/vegnetnews/2019/07/25/pumpkin-field-day/

Response to Cucurbit Growers Early to Mid Season

 

Make a Withdrawal from your Soil Weed Seed Bank: Stale Seedbank Technique

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.

Using Cover Crops for Weed Control in Spring

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.

Winter rye, forage radish, hairy vetch and crimson clover blend

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 city tilled the garden in late March, some of the cover crops persisted and will continue to grow without further tillage or herbicide application.

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.

 

Spray Drift 102

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).

Figure 1: Typical response of tomato foliage to low-dose (simulated drift) of 2,4-D.

Figure 2: Distorted growth of greenhouse tomato thought caused by fumes from incomplete combustion from wood heater. Photo courtesy of M. Badertscher (OSUE Hardin Co).

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).

Figure 3: Adventitious root formation on stem of tomato following 3 days of flooding conditions (root zone saturation).

Figure 4: Adventitious root formation on stem of tomato following exposure to low-dose 2,4-D.

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.

Figure 5: Characteristic basal-chlorosis of new tomato leaflets caused by glyphosate drift.

Figure 6: Occasional ‘auxin-mimic’ symptoms that occur in a small percentage of glyphosate drift events.


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.

2017 Pumpkin Field Day Approaching!

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.

Pumpkin plots at the research station.

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 (jasinski.4@osu.edu) or 937-462-8016 for more information.

Pumpkin field day flyer.

Eastern Ohio Vegetable Field Walk

Barnesville, OH

OSU Agricultural Extension Educators and vegetable producers in eastern Ohio welcomed Ohio State University Extension specialist July 25th for a vegetable production field day originating at Captina Produce Auction south of Barnesville. The Captina Auction began in 2005 and has increased production and sales each year since its beginning. A new 60’ addition was added this past winter to provide needed floor space to accommodate increased production. Approximately 100 acres of local vegetable produce is grown and marketed through the auction each year, predominantly by Amish growers.

The produce auction is named Captina Produce Auction due to its proximity to Captina Creek, a very high quality watershed and important water source in the community.  The local Amish growers have a very good reputation in their farming practices as well as the quality of produce they provide to homeowners, roadside stands, wholesalers and local grocers. 

Captina Produce Auction

Celeste Welty, entomologist, Sally Miller, plant pathologist, Matt Kleinhenz, vegetable crop physiology and management specialist, Doug Doohan, weed control specialist, and Jim Jasinski, integrated pest management coordinator came to provide a wealth of information to vegetable producers in the area.  The team provided diagnostic information for various insects, diseases and weeds encountered during the day along with many other recommendations for common vegetable production problems.

Dr. Doug Doohan addressed a question about using pesticides in vegetable production and effects on the environment. He was adamant that safety is always the first concern, but very positive and confident that safety measures are taken into consideration, with extensive testing, before products are marketed. Therefore, when growers use products at labeled rates, and as directed on the label, environmental impacts are negligible. Doug also provided valuable information for producers to help them control and reduce weeds. Timely applications of glyphosate in the fall can really be helpful to decrease hard to kill weeds such as Canada thistle he said. Eradicating weeds before plants are allowed to set seed is a practice all producers should strive for. One plant can produce thousands of seeds in a growing season if left unchecked.

Downy mildew, a potentially devastating cucurbit disease, was identified and eventually confirmed on cucumbers leaves as a result of the field walk.  This diagnosis, led into a discussion about downy mildew and Dr. Sally Miller made the point that the disease does not overwinter in Ohio. It blows in on wind currents from the south where it can overwinter and from Canada, where it is thought to overwinter in greenhouses. Downy eventually makes its way to Ohio during the growing season so growers were encouraged to keep close watch to detect the disease. It was brought up by the specialists, downy mildew might not be as devastating to an early cucumber crop in mid-July, but later crops are at much greater risk from this late season disease.

Observing pumpkins during the field day

Next to the cucumbers with downy mildew there was a very clean pumpkin patch that had not been sprayed with a fungicide. Dr. Miller discussed the different strains of downy mildew on cucumbers verses pumpkins.  Even though they are both in the cucurbit family, the variant of the downy mildew that infects each one is different.  This brought up a point of preventative fungicide sprays.  Once a field is severely contaminated, it usually is too late for fungicides.  A preventative spray program was recommended to keep the pumpkin field healthy and utilize various modes of action to prevent resistance.

 

Vegetable production discussion

Dr. Matt Kleinhenz provided information to the group about extending the growing season using hi-tunnels and discussed production and use of grafted vegetable plants. There is a growing market out there for this technology he said. Matt discussed how superior yields and increased disease resistance can be provided when the correct root stock is used. Heirloom tomato varieties, for example, really benefit when they are grafted to a root stock that has resistance to many problems growers deal with.

 

Dr. Celeste Welty discussed many insects with producers during the day. She provided specimen displays of beneficial insects and unwanted pests so each person could learn to identify ones they did not know. She said, many insects in vegetable crops are beneficial

Celeste Welty discussing traps

insects and growers need to know the difference. Integrated pest management starts with correct identification of the insect. At one-point a question was asked about cucumber beetles. Celeste discussed the different beetles and explained the process of how damage to cucurbit crops takes place. Early monitoring and control measures for this pest were stressed.  At the edge of a sweet corn field a Scentry Helothis trap was viewed by participants and Dr. Welty explained procedures for using this trap. This type trap is not to reduce pest numbers like many traps we use, but this is used to capture male moths and monitor flight numbers by using a pheromone to attract them into the trap. Threshold numbers were discussed and she explained how producers can use this information to make the most-timely applications of sprays to reduce corn earworm and European corn borer damage.  (Instructions can be found at)  http://u.osu.edu/pestmanagement/files/2014/12/CornTrapInstructions2009-u47rp3.pdf

The field walk provided growers a wealth of knowledge and the specialists were thanked for their participation and willingness to share information with growers in eastern Ohio.