Scouting Notes From the Wayne County IPM Program

Here are our weekly observations and notes from the fields around Wayne County from the week of June 20-24, 2022.

Vegetable Crops

Now is a critical time to be monitoring your cucurbit crops for cucumber beetles. Early populations may not seem as evident due to the presence of insecticide in treated seed, however, as the efficacy of the seed treatment diminishes, the cucumber beetle feeding will begin to increase. The threshold for beetles while the plants are in the 2-4 leaf stage is 1 beetle per plant. Once the plant is above the 4-leaf stage, the threshold increases to 3 beetles per plant. The greatest chance for impactful feeding damage and bacterial wilt infection via the cucumber beetle occurs during early season feeding.

Squash bug found in Wayne County on yellow squash. Cucumber beetles feeding in the background. F. Becker, 2022.

Also, of note in cucurbits, the excess moisture and warm conditions allowed for development of some phytophthora cases. If you suspect that you have plants infected by this pathogen, avoid spreading it in your fields by removing and destroying infected fruit and plant material. An integrated approach to managing this disease includes practices such as avoiding excess water, sufficient crop rotations and fungicide treated seed. Additional findings in cucurbits included squash bugs being found this week in an early planting of yellow squash.

An area of yellow squash plants lost due to phytophthora, F. Becker, 2022.

Continue to monitor onions for thrips populations. The recent heavy rain may have prevented populations from building, however, hot dry weather, combined with the increased size and number of leaves can provide the opportunity for thrips numbers to escalate rapidly.

In tomatoes our scouts noted some observations of early blight and Septoria.

Remember to check your crops for any signs of foliar diseases, especially with the amount of soil splashing that took place in the last few weeks. Bacterial and fungal diseases can be spread on the lower leaves of plants when heavy rains splash soil and pathogens onto the foliage. Overall, stress from high temperatures has been evident in a majority of the crops that we are scouting.

Small Fruit and Orchards

Male SWD, Thomas Becker photo, 2022

Female SWD, Thomas Becker photo, 2022.

Spotted winged drosophila have been caught in traps around Wayne County. As we move out of strawberry season into raspberries/blackberries/blueberries, the SWD populations will begin to increase leading to possible infestations in ripening brambles and blueberries.

In apples, we continued to find strikes of fire blight. Conditions have been ideal for fire blight development, although dryer conditions may hinder further development. This week we continued to find aphids in apple trees. Our IPM program identified populations of green apple aphids in several orchards as well as a case of wooly apple aphids. Both aphid species can cause significant damage at this time of year. Accordingly, diligent scouting is a crucial aspect to not allowing either of these aphid species from getting out of hand. The heavy rains likely knocked back some of these aphid populations, but it will be important to monitor aphid populations as dry conditions take hold.

We have had sustained catches (over threshold) of both Codling Moth and Oriental Fruit Moth in apple and peach orchards, respectively. Over the last week, both Codling Moth and Oriental Fruit Moth populations have been trending downward, however, numbers have still exceeded the thresholds.

Now is the time to be managing early season diseases in apples. Scab, rust and powdery mildew are the three main diseases of concern at this point in the season.

Once strawberry harvest is over, it is a good time to consider renovation of the patch. The goals in renovation are to reduce plant numbers by narrowing the rows, remove old foliage (reduces diseases), control weeds, and reduce insect pests. After renovation, regular irrigation and weed control are essential. High yields next year depend on having large, healthy, vigorous plants when fruit buds are initiated in late summer.

We have started catching grape berry moth in our traps.

Scouting Notes from the Wayne County IPM Program

Here are our weekly observations and notes from the fields around Wayne County from the week of June 13-17, 2022.

Vegetable Crops

The Colorado Potato Beetle larvae have hatched and are now feeding in both potato and eggplant. When approaching plants to look for them, be cautious. When the beetle is startled, they drop to the ground and may be difficult to see. They do significant damage to the foliage and can cause significant reduction in yield. The Colorado Potato Beetle also has a history of developing resistance to insecticides being used as control measures. This has limited our choices for treatment options. The best way to prevent further resistance is to avoid using the same insecticide repeatedly. At the current plant stage for potato, the threshold is approximately 1 beetle per plant. For eggplant, it is 25 beetles per 50 plants.

In summer squash/zucchini, we are seeing an increase in the number of cucumber beetles. The seed treatment on these plants is beginning to reach the end of it’s efficacy. For fall vine crops that have just been planted in the last week or so, that seed treatment should still have a few weeks of efficacy left.

In onions, we have noticed an increase in the number of thrips, in many cases approaching an action threshold. Threshold is 25-30 thrips per plant. This week we also found more incidences of slippery skin which was confirmed by the vegetable pathology lab at OARDC earlier this month. Slippery skin is caused by Pseudomonas gladioli. This bacterium is spread via soil splashing from heavy rains and enters the plant through natural openings or openings from mechanical injury. Given the heavy rains we have experienced in the past week, it would probably be a good idea to get out and check your onions.

Overall, tomatoes are continuing to grow rapidly in the greater Wayne County area, with some plantings of field tomatoes beginning to set blooms. We did have a case of timber rot identified in the West Salem area in field tomato. It is important to practice good crop rotations and rotate out of a crop family completely for at least 3-4 years. A complete crop rotation will help to break up disease and pest cycles. Similar to onions, tomatoes can contract bacterial diseases from soil splashing. If you have tomatoes, it may be worthwhile checking the lower canopy of your plants to monitor the presence of any diseases.

Our IPM pest scouts have continued to find Mexican bean leaf beetles in the green beans this week. Light foliar feeding was observed.

With the warmer weather and plants maturing rapidly, the slug threat has greatly reduced in the last week. Any new transplants should still be monitored for feeding, however there should be less of a slug presence for the rest of the growing season.

 

Small Fruit and Orchards

This week we continued to find aphids in apple trees. Our IPM program identified populations of green apple aphids in several orchards as well as a case of wooly apple aphids. Both aphid species can cause significant damage at this time of year. Accordingly, diligent scouting is a crucial aspect to not allowing either of these aphid species from getting out of hand. The heavy rains likely knocked back some of these aphid populations, but it will be important to monitor aphid populations as the weather dries out a bit.

In apples, we continued to find a few instances of fire blight. Conditions have been ideal for fire blight development, so it is not much of a surprise to see some cases.

We have had sustained catches (over threshold) of both Codling Moth and Oriental Fruit Moth in apple and peach orchards, respectively. Over the last week, both Codling Moth and Oriental Fruit Moth populations have been trending downward, however, numbers have still exceeded the action thresholds.

With the storms over the course of the last week, it is not unlikely that we will see some yield loss from wind, heavy rains, or hail damage in many of the area’s fruit trees.

Now is the time to be managing early season diseases in apples. Scab, rust and powdery mildew are the three main diseases of concern at this point in the season.

Strawberry leaf diseases may appear unsightly right now, however, now is not the time to be managing these leaf diseases. Once harvest is done and during patch renovation it is recommended that you address these concerns, either with a fungicide or with resistant plant varieties. This is also a critical time to be watching for fruit rots such as Botrytis.

Grapes are currently around the buckshot berry stage. It is still possible to spray for and manage black rot during this time.

Mechanization-Automation in Vegetable Production: It’s Personal and Important

The big picture is that (vegetable) farming has been mechanizing and automating aggressively for more than a century, although the pace seems to be accelerating and the range of tasks targeted for improvement seems to be increasing. There are many reasons for these trends, but all may come down to the fact that technology that addresses peoples’ needs is personal and, therefore, important. Indeed, read nearly any issue of The American Vegetable Grower Magazine (or its online counterpart https://www.growingproduce.com/), The Vegetable Growers News (https://vegetablegrowersnews.com/magazine/), or other farmer-focused magazine, blog, or newsletter, watch videos or listen to podcasts, or attend industry programs and you will be exposed to personal stories of how specific machines or pieces of equipment are assisting growers in some new way at some point from seeding through post-harvest handling. Stories come from input suppliers, growers, people in extension and research, equipment manufacturers and retailers, and others. Collectively, these stories have given me many lessons but three will be highlighted here.

First, overall, mechanization and semi- to full automation of core farm activities will continue. Trends begun long ago are fully established with incentives to mechanize/automate increasing and obstacles to the process decreasing. Second, growers have various options now and will have others going forward. “There’s an app for that” was popularized about thirteen years ago (and trademarked soon after). However, it now also seems to apply to equipment or machines designed to help farmers since some see nearly every major vegetable seedling or crop production activity historically requiring people as eligible for some form of mechanization or automation. GPS and/or laser-guided automatic weeders/cultivators demonstrated at a recent industry program in Ontario, Canada (https://onvegetables.com/2022/02/28/tomato-day-coming-on-march-10-2022/) and available for rent were especially impressive to me, although many other examples of grower-friendly options are available or in the pipeline (e.g., “scouts,” sensors/actuators, samplers, seeders, transplanters, sprayers, harvesters, etc). Examples are often on display at conferences, tradeshows, and expos in and around Ohio and farther away (e.g., https://www.worldagexpo.com/ – see list of exhibitors at 2022 program). It is also important to note that some machines or pieces of equipment are being designed with more than completing the task in mind (e.g., environmental sustainability). The third lesson available from paying attention to mechanization-automation in the vegetable and specialty crop sector is that off-the-shelf technology that reduces down-time, increases efficiency and/or productivity, or provides other benefits is increasingly practical to an increasingly diverse range of vegetable growers, regardless of the size, location, or other characteristics of their operation. Formerly most relevant to very large, heavily capitalized operations, current generations of machines and pieces of equipment are available to a much larger group of vegetable farms. Some developers, manufacturers, and retailers are more willing to discuss or offer: a) machinery and equipment applicable across more production conditions (including farm size) and b) lease or lease-to-own access. So, access to viable options for mechanizing-automating is increasing, and the time may be right to experiment on your farm.

There is much to consider and a lot at stake when mechanizing-automating and various approaches are used. The farmers responsible for https://www.growingproduce.com/vegetables/why-one-small-vegetable-farm-adopted-mechanization/ emphasize relying on input from other farmers, including via YouTube. Going forward, we will feature grower experiences with tools improving vegetable production we are helping pilot, including systems increasing the efficiency and effectiveness of high tunnel ventilation (temperature, humidity) management.

Why Aren’t My High Tunnel Tomato Plants Growing Faster?

Beginning about now and lasting through mid-April, I am often asked by high tunnel tomato growers why their crop is not developing as rapidly as they expect. Troubleshooting covers a wide range of possible explanations. As various ones are considered and ruled out, the possibility they have overlooked the role of soil temperature becomes more important. The high tunnel may be heated, and the crop may have been irrigated and fertilized aggressively, but there is usually no record of the soil temperature, which greenhouse growers know is very important and work to optimize. After all, root growth significantly influences shoot growth and root growth is influenced by soil or root zone temperature.

In my view, we know far too little about soil temperatures in high tunnels — what the optimal ones are at any time and how to achieve them. Still, discussing this with people in Ohio and other states and having done some research on the topic, I was asked to summarize findings at the recent Mid-Atlantic Fruit and Vegetable Convention in Hershey PA (https://www.pvga.org/wp-content/uploads/2022/01/Mid-Atlantic-Convention-Program-22-website.pdf). The subject of the presentation was “root zone heating and root zone temperatures for high tunnel growers” and what follows are a few messages from that presentation.

Root systems are rarely seen but their size, form, and function influence every aspect of the crop, including the size of the canopy and crop marketable yield and profit potential.

Root systems are hard-wired to follow general patterns as they develop. However, conditions surrounding root systems influence their development significantly. Further, those conditions include temperature and are partially set by the grower. So, growers are partially responsible for root system development and function. While a “strong” canopy is good evidence of an equally strong root system, without another canopy to compare it to, it is difficult to be sure it is as strong and productive as it could be. This indicates that a little on-farm experimentation can go a long way in helping optimize total crop management. It also reminds us that since we usually cannot see roots while experimenting or farming, we often need to rely on tracking factors we can measure and that are known to influence root system development and function.

Research findings suggest that tomato growth and production tend to be greatest at root zone temperatures of 65-70 degrees F. This begs two questions.

First, are root zone temperatures in your high tunnel in the optimal range as often as possible? Do you measure soil and irrigation water temperatures? We have recorded soil temperatures every fifteen minutes for various entire seasons in high tunnels and open fields at OSU-Wooster/OARDC and some of the data are shown below (click to enlarge, if needed). Notice the description of the situation in which the readings were taken and when soil temperature readings were in the optimal range. These readings may or may not represent your farm or crops. However, the data may give clues as to the potential temperatures in your fields and high tunnels and encourage you to record those temperatures directly. Reliable, easy to use, inexpensive instruments are available for doing that.

About irrigation water – much of it draws from wells and surface sources and can be very cold (from the crop’s perspective) fall through spring. Although it has not been tested to my knowledge, passing well, surface, or municipal water through drip lines in a high tunnel, heated or not, may be unable to bring its temperature to 65-70 deg F. So, irrigation in the earliest part of the season may amount to bathing roots in water well below the optimal temperature for tomato and other crops and heating the air may overcome that issue only partially.

This brings us to Question 2. Are you convinced that your returns on investments in high tunnel heating, especially of the air for early season tomato production, are as high as possible? If the air temperature is high but soil temperature is low, are you getting as much from the relatively short photoperiods as you could? In early spring, crops may be more limited by a lack of sunlight than below-optimal air temperatures (and excessive heating during extended low-light periods may be counterproductive). We cannot change daylength or cloud cover, but we have some control over air and soil temperatures and may benefit from bringing investments in them into alignment with daylength. For example, should heating increase with daylength? What is the return on investment in aggressive air heating when daylength is very short soon after transplanting?

Addressing those questions opens doors to exploring the relative value of investments in air, soil, or combined heating. That is a subject for other discussions and articles, but it is worth asking if investments in air heating are returning as much as we expect based on the air temperature alone. The 11/6/21 issue of VegNet included an article on root and air heating in fall-time high tunnel leafy vegetable production (https://u.osu.edu/vegnetnews/2021/11/06/soil-heating-effects-on-days-to-harvest-quality-and-regrowth-of-three-high-tunnel-and-fall-grown-vegetable-crops/) and our previous research included spring season experiments, too. Individual crops respond differently to air and soil temperature due to biology and other reasons. For example, the growing tip of lettuce plants is closer to the soil surface than the growing tip of tomato plants and, therefore, may be more strongly impacted by root zone temperature and heating over brief periods.

The point here is that investments in high tunnel heating may be most effective when taking the whole cropping cycle and rotation into account. High tunnel management systems, including temperature, can be designed around one or a set of crops – i.e., around optimizing income from one crop or across the year. Of course, this would occur on a farm by farm, market by market basis. This spring and season, as you are able, consider taking a moment to examine your high tunnel temperature management practices and ask if they maximize your entire annual profit potential.

Solar Energy and Your Farm

Whereas photosynthetic organisms convert light to chemical energy, solar panels begin the process of converting light to electrical energy. No one is isolated from the effects and importance of photosynthesis, and it seems that a growing number of people are increasingly reliant on and affected by solar energy in one way or another, too. Farmers and other landowners in Ohio and throughout the U.S. are currently intersecting directly with solar energy in at least four ways. They are using solar energy from the grid, weighing options for leasing land to solar energy projects adding to the grid, exploring options for integrating farming and solar energy production (the process of “agrivoltaics”), and/or they are experimenting with using electricity they generate using solar capture completed as a ‘private’ activity.

What to look for as you considering leasing land for solar energy development is the subject of three free webinars organized by Penn State University Extension. The webinar held on February 23, 2022 featured Scott R. Kurkoski of Levene Gouldin and Thompson, LLP (https://www.lgtlegal.com/) as the technical presenter. His comments were very practical and informative, especially for landowners in the early stages of evaluating a potential relationship with a solar project. Watch the webinar at https://psu.mediaspace.kaltura.com/media/Leasing+Your+Land+for+Solar+Energy+DevelopmentA+Webinar+on+2-23-22/1_xt3id0rt and consider registering for the webinars to be held on March 16 (Evaluating the Contract Terms When Leasing Your Land for Solar Energy Development; www.bit.ly/solarMarch16) and March 23 (Solar Leasing Questions, Answers, and Wrap-up; www.bit.ly/solarMarch23). Or contact Tom Murphy of Penn State Extension for more information (tbm1@psu.edu) on the webinars.

In an article posted to VegNet on December 19, 2021 (https://u.osu.edu/vegnetnews/2021/12/19/a-simple-inexpensive-diy-system-for-controlling-the-height-of-high-tunnel-sidewall-rollbars-remotely/), I outlined a small but important project involving electricity generated by one solar panel attached to a high tunnel at OSU in Wooster. That panel and the battery it charges has powered an inflation fan, sensors collecting temperature data, four motors driving end wall vents and sidewall motors, and the panel controlling them all nonstop for more than six years. The battery has been replaced once. This is one small example of how on-site solar power generation can benefit a grower.

What happens to and/or can be done with land beneath a large array of solar panels setup to supply the grid (or local operation) is a major question for landowners and solar project officials alike. Officials with no interest in using the land for an additional purpose still tend to require it to be maintained to a basic extent so the project is not compromised. However, in other cases, landowners (farmers) and solar officials explore the “agrivoltaics” (AV) option. Two broad versions of agrivoltaics are taking root but progressing at slightly different rates. In one, land near the solar panels is grazed (e.g., by small ruminants) mainly to control vegetation but also to help generate revenue. In the second version, revenue-generating crops (vegetables? forages? fruit? flowers?) are grown on land beside or below the solar panels. Water released through plant leaves cools the panels by evaporation and reduces the heat-island effect common in solar panel-only facilities. Therefore, the panels operate more efficiently in converting sunlight to electricity. Other potential benefits of AV include more efficient water and land use, less heat stress on plants and panels, and more energy capture – meaningful financial and environmental gains. Clearly, the ‘trick’ is in designing the system to serve and optimize as many functions as possible.

Not surprisingly, agrivoltaics is regarded as a potentially significant partial solution to complex and widespread challenges. AV combines solar power generation and farming. Normally, these processes occur independently and separately. AV theory integrates them in exciting ways by requiring the processes to occur simultaneously on the same land. Early-stage test results in parts of the U.S., Europe, and Australia have created optimism. However, significant challenges exist in integrating photovoltaic power generation and agriculture on working farms. In May, I will be fortunate to begin collaborating with experts at Central Queensland University in Rockhampton, Queensland, Australia and industry partners in identifying the best next steps in utilizing agrivoltaics more effectively, including in Ohio and the region. This Fulbright-supported project will help ensure a rapid and effective transfer of understanding and capacity between OH/the U.S. and Queensland/Australia. Look for updates in these pages and other outlets or contact me anytime for more information on the project.

Ohio Grape Grower Survey

The Ohio grape industry produces grapes for wine, juice, and table grape use. Over the last decade, the industry has grown rapidly in our state. Unfortunately, the USDA ceased conducting a regular Ohio grape census five years ago, making it difficult to track this growth or collect accurate information about the number of acres and production by grape variety. To fill this gap, the Ohio Grape Industries Committee has commissioned researchers at The Ohio State University to conduct an independent survey of all Ohio grape growers.

Dr. Douglas Jackson-Smith, a professor in the College of Food, Agricultural, and Environmental Sciences at Ohio State, is leading the survey effort which is designed to reach all Ohio producers who grew wine, juice, or table grapes in 2021. Beginning the third week of January, researchers will send the survey to a comprehensive list of grape growers in the state, with an opportunity to respond through the mail or online.

The survey is voluntary and all responses will be treated as confidential. To get an accurate picture of the size and scope of the current Ohio grape industry, it will be critical to hear back from all producers. Aggregated results will be shared in a report that will be available to farmers, wineries, juice processors, and others to inform their decisions.

If you are a grape grower and do not receive a copy of the survey or if you have questions about the project, please reach out to Dr. Jackson-Smith at Jackson-smith.1@osu.edu or 330-202-3540.

 

A Simple, Inexpensive, DIY System for Controlling the Height of High Tunnel Sidewall Rollbars Remotely

The Problem

High tunnel growers come to know through trial and error and some hardship that their success depends on managing the temperature and other conditions inside the high tunnel with care. That is, that maximum yield and quality are possible only when conditions inside the tunnel and near the crop are optimal as often as possible. High tunnel growers also come to learn that achieving optimal conditions round-the-clock and day after day is difficult and costly in various ways. For example, it is difficult because crop needs and conditions outside the tunnel can change dramatically and quickly, especially during key points in the crop cycle in spring and fall. Reacting to changes in crop need and other must-dos on the farm can be challenging. Managing temperature and other conditions inside the tunnel usually also requires undesirable investments in time, effort, and money. Of course, conditions inside the tunnel are usually set by controlling the extent to which sidewalls, vents, and/or doors are open, with the height of sidewall rollbars being particularly significant. The trouble is that the position of most sidewall rollbars is set by hand. This requires the grower or another person to stop what they are doing, travel/go to the high tunnel, and reposition the rollbars manually. This commitment and expense are unfortunate enough. However, the fact that it may need to be done multiple times per day for many days in a row for conditions near the crop to remain optimal becomes problematic for many high tunnel growers. They are required to choose between: (a) continually repositioning sidewall rollbar heights (“babysitting” the tunnel) at some direct cost and at the expense of engaging in other activities or (b) setting sidewall rollbar position at a “compromise” height and accepting the consequences of conditions (e.g., temperature, wind) being above- or below-optimal for potentially lengthy periods. In our view, high tunnel growers should not be required to have to make that choice.

Existing and New Solutions

Various companies (e.g., https://www.advancingalternatives.com) agree and offer automated ventilation control systems involving sensors, a control panel, and sidewall motors. We have had a version of the Advancing Alternatives system on a moveable Rimol high tunnel since 2015 and have been very pleased with both (control system, high tunnel). The high tunnel’s sidewall motors, endwall vents, inflation fan, and control panel are all powered by a standard 12-volt battery charged by one medium-size solar panel. It’s an impressive system. However, we are also aware that fully automated approaches to ventilation can cost more than some growers are willing or able to pay and place control of the high tunnel conditions largely in the hands of the control panel, not the grower.

Therefore, we have been working to develop a low cost, DIY way to control sidewall motors remotely that keeps the grower directly in control of sidewall position (e.g., to account for conditions that a fully automated system may not monitor, at least without additional cost).

Alex Herridge will soon complete his undergraduate degree in Computer Science and Engineering at The OSU and his contributions to the effort have turned the idea for this alternative, grower-friendly system into reality. Full plans for the system will be available in a separate publication soon but its key features include:

1. Standard sidewall motors powered by a battery-solar panel combination, as described above;
2. A standard voltage-regulating unit converting 12 volts from the battery to 24 volts needed by the motors (approx. $80.00);
2. A motor controller (available at electronics stores or online for approx. $15.00);
3. An off-the-shelf, WiFi-enabled microcontroller to act as the brains of the system (approx. $5);
4. WiFi already present on the farm property or wireless access with a hotspot or similar ($0 to monthly charge typical of a mobile phone plan); and
5. Code for the motor controller (no charge).

To proceed, motors are attached to sidewall bars and powered and a basic network connection linking the grower’s phone (or other device) and the microcontroller is established. The entire process can be completed in approximately four hours once all materials and WiFi are on site. Thereafter, the sidewall motors can be controlled with one’s mobile phone or other linked device using a simple interface setup for the purpose. Pictures of the preliminary, bare-bones version of the interface we used to raise and lower a sidewall bar on a high tunnel at OARDC on December 13 are given here. The bottom-line of this approach and system is that it will allow growers to raise and lower sidewalls from wherever they have internet access using low cost, off-the-shelf hardware. Watch for additional posts regarding this system at VegNet and other locations and contact me (Matt Kleinhenz; kleinhenz.1@osu.edu; 330.263.3810) if you are interested in learning more about or testing the system on your farm.

(OSU Computer Science and Engineering student with the motor and micro controllers and standard battery charged by a solar panel.)

(Exterior of the Rimol moveable high tunnel and the solar panel used to charge the battery powering rollbar motors, endwall vents, inflation fan, and control panel.)

(Simple, password-protected interface for controlling sidewall rollbar position. Usable from anywhere the owner has internet access and allowing them to control sidewall rollbar height remotely.)

 

 

 

 

 

Soil Heating Effects on Days to Harvest, Quality, and Regrowth of Three High Tunnel- and Fall-grown Vegetable Crops

Grower interest in fall-to-spring marketing of crops freshly harvested from high tunnels is increasing, along with the number and types of questions they have about the production side of the process. Excellent resources and information are available on major aspects (e.g., crop selection, planting schedules) but growers continue to seek and test cost-effective steps to enhance yield and/or quality. Managing temperatures near the crop so they maximize yield and quality has become a major focus for some. We say “temperatures” because root-zone and above-ground temperatures are often different and influence crop development and composition differently. So, we have been studying the effects of common production materials and strategies used to alter temperatures near the crop for many years. Experiments have included various combinations of row covers (film, fabric) to increase air temperatures (primarily) and soil heating. The most recent experiment was started in September and is described in the five panels below. Please contact us (Matt Kleinhenz; kleinhenz.1@osu.edu; 330.263.3810) if you would like more information, have questions about your production methods, and/or would like to discuss collaborative research that could be completed on your farm.

 

Optimizing Film, Fabric, and Root Zone Heating Combinations in Fall-to-Spring High Tunnel Vegetable Production

An increasing number of growers look to harvest and market vegetables grown in high tunnels fall to spring. Selling freshly harvested material (e.g., leafy, root, and other crops) from roughly October through April appeals to some farmers but it also raises many production-related questions in practice. Many of these questions relate to the use of plastic films, fabric row covers, and supplemental heating (including of the root zone). Questions such as which ones to use, when, for how long, under what conditions, and in what combination are common. The Vegetable Production Systems Lab has completed research in this area for more than fifteen years, cooperating with farmers often and using high tunnels at OARDC in Wooster which range in size, approach (conventional, organic; flat ground, raised beds), and other characteristics. Findings from these experiments have been summarized in publications (including VegNet) and during programs around the Eastern U.S. Our newest experiment was initiated on Sept 23 and includes the 20 wood-framed raised beds shown here, each seeded to either Scarlet Nantes carrot, Outredgeous lettuce, or Ovation greens (Brassica) mix from Johnnys Selected Seeds. This experiment will examine the influence of daily (8 am – 5 pm) root zone heating (accomplished with electric cables placed approx. 7 inches below the soil surface) in combination with vented plastic film row cover on crop development, yield, and quality. Vented plastic film covers all twenty plots (beds) while daily root zone heating occurs in ten of the twenty plots. Root zone heating will be discontinued at six weeks after seeding but the film will remain in place through final harvest in December. These treatments were chosen partly because two findings have been common in previous research. First, crops (e.g., lettuce, Brassica greens, carrot) and varieties have responded very differently to the use of film, fabric, and root zone heating — whether used alone or in various combinations. The same trend appears to be underway given the relative sizes of the crops shown in the pictures below (taken 10/9/21; carrot at top, Ovation Brassica mix in middle, lettuce at bottom). Second, in this experiment, we are very interested in root zone heating as a supplement to the above-ground heating that occurs with film in place and is typically pronounced September to early November and late January through March. Finally, temperature and relative humidity are recorded in each plot every five minutes, allowing us to describe treatment effects on these conditions very reliably. The sensor unit shown in the bottom-most picture below also relays the temperature and relative humidity readings to the “cloud,” allowing us to see the numbers in near real-time. This battery- and solar-powered Hobolink monitoring and reporting system from Onset Computer Corporation has been in place for more than two years and has greatly enhanced the efficiency and effectiveness of our high tunnel ventilation management across the ten tunnels in our program.

 

Grafted Watermelon Plants: Under What Conditions and Practices Does Using Them Offer the Best Return on Investment?

A lot of research is focused on answering that two-part question for watermelon and other crops (e.g., cucumber, cantaloupe, tomato, pepper). Full answers will emerge as growers and researchers share and integrate their experiences then evolve as circumstances change. Currently, most agree that using grafted plants is most beneficial when a resistant rootstock is selected to help offset the effects of a significant soilborne disease (e.g., Fusarium, Verticillium), regardless of crop. However, rootstocks with additional traits are being tested under other troublesome conditions (e.g., salinity, heat, cold, drought, flood). Growers are encouraged to listen as peers and research-extension and industry personnel share new information on the performance of grafted plants under various conditions. Information will be specific to crop, setting (field, high tunnel), system (conventional, organic), market, farm size, and other key variables.

Soil and other production conditions are not the only factors that influence the value of grafted plants to growers. Practices used to grow the plants are also important. Plant and row spacings (plant populations), irrigation and fertility programs, and planting and harvesting dates may also affect growers’ experiences with grafted plants.

Industry-research/extension partnerships can help fast-track arriving at answers to where and how grafted plants should be grown for growers to benefit most. We work with plots at OSU and on farms to understand the impacts of in-row spacing, fertility programs, and more on watermelon fruit yield and quality. Grafted and standard (ungrafted) plants are included in each experiment. Results from a multi-year study in Wooster through 2020 are summarized in a short video at https://go.osu.edu/vegeprosystemslab. Overall, fruit number and total weight have been significantly greater in grafted plots and at an in-row spacing of five versus four feet (between-row spacing of six feet in all cases). The results suggest growers can reduce plant populations but increase yield meaningfully – i.e., reduce plant costs while increasing income potential. Importantly, evidence of Fusarium in this experiment has been absent or minimal in all previous years. As explained and shown in the panels below, Fusarium is affecting the experiment significantly in 2021. Standard (ungrafted) Fascination and Sweet Dawn plants are very weak or dead while grafted versions of both (Carnivor, Pelops as rootstocks) remain healthy and vigorous. Harvest will begin soon and fruit yield data will be available by season’s end. Please contact me if you would like more information on this experiment or grafting.