Author: Matthew Kleinhenz

Daylength Effects on Seeding/Transplanting Dates for Fall-to-Spring Harvesting of Annual Specialty Crops

Whether growers are creating, discovering, or connecting with previously untapped markets, much is happening in Ohio annual specialty crop production that affects when crops are established and harvested and how they are managed in between.

For example, growers working with increasingly diverse markets must provide vegetables, flowers, herbs, and other crops meeting specific standards for size, color, weight, and other characteristics. Evolving standards continue to alter the mix of crops consumers/customers seek and/or their form – steadily rising interest in crops enjoyed around the world, micro or baby greens, small potatoes, and personal size melons are four common examples among many others.

Also, some markets are looking for Ohio or regionally grown products over more of the calendar year, challenging historical perspectives on seasonality.

Questions about seeding and transplanting dates naturally follow from these developments, especially since Ohio growers: (a) operate in locations with variable growing conditions and (b) use open field and/or semi-protected systems featuring low, mid, and/or high tunnels, creating additional complexity and opportunity.

Typical basic practice is to circle target harvest dates and confirm expected crop maturity, then count back to ideal seeding or transplanting dates, estimating based on likely near crop environments and other factors. As such, possible crop responses to light-temperature combinations expected to occur from seeding/transplanting onward are key. Selecting proper seeding/transplanting dates when only natural sunlight will be available relies on a few key principles.

For example, “growth” is defined as an increase in the amount of plant biomass whereas “maintenance” refers to the persistence of that biomass. Growth tends to require more light than short-medium term maintenance. This is one reason why established or harvest-ready crops can be maintained for weeks to months in various settings in fall-winter after growth has stopped due to much shortened days. Indeed, getting crops to market-ready status before growth stops due to inadequate light availability then maintaining them in saleable condition for weeks after is a core goal for many who produce and market fall-winter. Others look to get crops to a stage allowing them to overwinter successfully then complete growth and mature in early spring. Still others who also want to be first to the new year’s markets want to know how early seed or transplants can be set in late winter to utilize every available part of the expanding growth period. In all cases fall-to-spring, optimal temperatures help plants utilize whatever light is available but warm temperatures cannot fully replace or make up for low levels of light. In fact, high temperatures when light levels are unable to support growth are usually detrimental. This is one reason why some growers ventilate to cool their crop-filled high tunnels during clear but short days winter and early spring.

Crops differ widely in the amount of light (intensity x duration) required for them to grow. One rule-of-thumb is that most crops produced with sunlight only require at least ten hours of daylight to grow. Daylengths in Ohio are ten hours or longer between January 27 and November 14, on average. (You can see year-round daylengths at your location at https://www.timeanddate.com/astronomy/usa). Therefore, it is reasonable: (a) to target November 14 (on average) as the date by which most fall established crops should reach saleable condition and (b) to expect crops seeded or transplanted around January 27 (on average) to grow at rates tracking the increasing daylengths; i.e., very slowly at first and increasing as light levels increase. However, there are two important exceptions to these rules-of-thumb. First, some crops can grow when using sunlight alone when daylengths are less than ten hours but need to be identified carefully. Second, as mentioned earlier and shown in https://u.osu.edu/vegnetnews/2024/02/03/a-minimalist-approach-to-ensuring-fall-through-spring-vegetable-harvests/, https://u.osu.edu/vegnetnews/2024/02/17/high-tunnel-crop-and-market-period-diversity/, and grower experience, mid-late fall can be an excellent time to establish crops able to over-winter and mature early the following spring (e.g., garlic, carrot, some Brassicas), before or while new crops are being seeded/transplanted. Crops with this ability can further expand harvest and marketing periods.

Seeding/transplanting windows for many annual specialty crops expected to be harvested in 2024 or early in 2025 from naturally lit open field, or low, mid, and/or high tunnel plantings remain open but informed steps should be taken soon to utilize the time that remains.

Using Each Season and Crop as Preparation for the Next in High Tunnel Production

Tomato production dominates main season, summertime high tunnel use but presents challenges. Like an increasing number of growers, we experiment with ways to maintain high tunnel soil productivity and profit potential for the long-term. Our operating principle is that crop and market diversity are useful and while some crops offer less income potential, their contribution to the success of the farm may not rest entirely in their specific balance sheet. Our posts on 10/28/23, 2/17/24, and 7/27/24 provide additional information and highlight some of our recent and ongoing work focused on ensuring year-round success in high tunnel production. Recent activities involving butternut squash, a mixed-species summer cover crop, and various vegetable and flower crops are summarized below.

Three panels focused on a mixed-species summer cover crop (cowpea, Italian ryegrass, pearl millet, and sorghum-sudangrass) seeded on 6/5/24 and terminated on 8/20/24.

As before, other HTs at our location are also being used to test and illustrate additional year-round production options involving crop selection and HT environmental management. Pictured is a small subset of the crops harvested or soon to be harvested since March-2024 (see https://u.osu.edu/vegnetnews/2024/02/03/a-minimalist-approach-to-ensuring-fall-through-spring-vegetable-harvests/) for a summary of crops harvested 11/23-3/24.

 

A Better High Tunnel Poly Covering?

High tunnel growers have long used standard 6 mil poly film to cover their structures. Standard 6 mil poly film is the “covering” workhorse of the high tunnel industry. However, as most high tunnel growers know, standard 6 mil poly film can be punctured easily, will continue to tear if cut, eventually becomes brittle and less transparent, retains very little heat energy, and allows sunlight to escape the high tunnel without contributing to photosynthesis, which hampers growers wanting to maximize growth fall-to-spring. Regardless, standard 6 mil poly film needs to be replaced every three to five years in many locations. While many growers may not give the film that covers their high tunnels much thought, it is usually the only thing that separates their crops from the outside and it influences their success in many obvious and not so obvious ways. Therefore, it is reasonable for growers to seek and expect improved high tunnel coverings just as they expect better versions of all other materials used on the farm.

We are pleased to be cooperating with the Seaman Corporation of Wooster, Ohio (https://www.seamancorp.com/), long known as an industry leader in high performance industrial fabrics. Together, we are evaluating the company’s exciting new experimental reinforced poly film which is far stronger and more puncture and tear resistant than standard 6 mil poly film and has other interesting properties that may, for example, allow it to supplement or replace hard polycarbonate in some applications.

As depicted below, HT 103 on the CFAES-Wooster campus currently contains a crop of butternut squash and was covered with the new film on 8/12/24. HT 204 is about 100 ft east of HT 103, identical in shape and age, covered with standard 6 mil poly film, and holding butternut squash. Going forward, cropping, ventilation, and other practices will be the same and environmental conditions will be monitored in both high tunnels. Therefore, overall, differences in environmental conditions and/or crop status in the two high tunnels are likely to result from their different coverings. Monitor temperature and relative humidity in high tunnels 103 and 204 and six other structures at the same location at https://u.osu.edu/vegprolab/resource-1/ and stay tuned for updates on this important evaluation.

Crop Selection and High Tunnel Soil Productivity

Crop selection and soil management and long-term soil productivity are interconnected. Many high tunnel soils are:
a) cropped repeatedly to relatively small sets of input-demanding crops,
b) disturbed frequently and intensely by cultivation and preparing for seeding and transplanting, and
c) exposed to persistent foot and equipment traffic.

High tunnel soils also tend to experience potentially troublesome temperature and moisture profiles. As a result, high tunnel soils can:
a) lose structure and become less friable and more compacted,
b) decline in organic matter,
c) increase in salinity, and
d) develop problematic nutrient imbalances and pathogen loads.

These and other challenges can lead high tunnel soils to become less productive – to require greater and greater amounts of cash and effort to maintain marketable yields at desired levels.

Including additional, less demanding cash and non-cash rotation or cover crops in high tunnel production schedules can help maintain soil productivity and offer other benefits.

Five 21 ft x 48 ft high tunnels used intensively in organic vegetable production-related research for 15-21 years are currently being cropped to butternut squash or a mixed-species summer cover crop (cowpea, Italian ryegrass, pearl millet, and sorghum-sudangrass). See representative panels below. The mixed-species cover crop has produced significant amounts of foliar biomass and suppressed weed growth effectively. Its root system is expected to provide multiple benefits. Similarly, squash plant growth and flower production have been excellent and fruit set is encouraging. Nine-hundred pounds of composted dairy manure were spread in each high tunnel on 4/16/24 and lightly incorporated but no fertilizer or crop protectants have been applied since. Both crops have been overhead irrigated (see https://u.osu.edu/vegprolab/crop-environment-publications/installing-an-overhead-irrigation-system-in-a-high-tunnel/).

Sections of other nearby high tunnels have been planted to buckwheat, carrot, Swiss chard, choi, dry bean, edamame soybean, garlic, groundpea (winter cover), kale, lettuce, okra, pepper, sunflower, and/or wheat (winter cover) since October-2023.

Cash crops can be harvested from high tunnels year-round in Ohio. Maintaining the productivity of soils that help make that possible is key. Considering what many cash and non-cash crops can offer to the process is useful.

Foliar Feeding of Vegetable Crops: An Overview of Why, Why Not, and What to Consider

The number of vegetable growers who are either curious about foliar feeding or using the practice routinely has risen in recent years. Foliar feeding has become a major component of the crop management plans of some vegetable growers while other people are concerned that too many growers rely too heavily on the practice. Let’s review some basic information specific to the process to improve decision-making about it.

1. It is true that plants can absorb nutrients through their leaves. However, it is also true that absorption differs with leaf age and condition, among individual nutrients, and based on other factors. Overall, young leaves tend to take-in nutrients more readily than older ones but are also more easily damaged by caustic solutions. Also, while micronutrients are absorbed at higher rates than macronutrients, micronutrients are present at sufficient levels in most complete soil-applied fertilizers or can be added to them effectively. Similarly, nutrients must reach specific locations in the plant regardless of where they enter it and may be less likely to do so at needed levels after entering through leaves instead of roots. Finally, nutrients entering through leaves and moving within the plant does not guarantee that the application will affect it in ways increasing profit. So, consider the following when asking what role, if any, foliar feeding will have in your comprehensive nutrient management plan: a) relative need for various nutrients, and b) nutrient absorption/uptake rates, mobility, effects once in the plant based on where they enter, and availability in different fertilizers.

2. Proponents of foliar feeding mention that it can: a) be highly tailored, b) bypass soil-based issues, c) lessen the potential for leaching or other losses, and d) create quick responses that may boost crop quality and/or reduce or help plants recover from stress. However, it is also important to consider major concerns with foliar feeding as a primary, routine practice, including how it: a) can damage leaves and fruits, create nutrient imbalances, facilitate the onset and/or progression of foliar disease, and contribute to runoff, b) usually has only short-term effects (requiring repeated use), c) should be done during specific environmental conditions which may not occur during large portions of the season, and d) requires great care to balance risks/rewards and costs.

Therefore, on balance, it is best to:
1. Consider “foliar feeding” as a supplement to, NOT a replacement for a comprehensive nutrient management program in which nearly all fertilizer is applied to the root zone. Strengthening root zone-based delivery programs will address the clear majority of nutrient management questions and challenges. Focus on specific and unique situations in which foliar applications MAY be useful instead of utilizing them as a rule or standard practice.

2. Be clear about the challenges associated with foliar feeding as a routine practice and experiment with it carefully. Select the key crop and crop stage and use the right material, at the right rate, and at the right time (under the required conditions), being sure to check solution chemistry and monitor crop condition.

For Additional Reading:

https://ipm.missouri.edu/mpg/2019/4/foliarFeeding/

https://s3.wp.wsu.edu/uploads/sites/403/2015/03/foliar-feeding.pdf

https://crops.extension.iastate.edu/blog/aaron-saeugling/foliar-feed-or-not

Blotchy Ripening of Tomato Fruit: Description, Contributing Factors, and Prevention

Marketable yield is more important than total yield. Physiological disorders like ‘blotchy ripening’ typically do not affect total yield but do reduce marketable yield, which reduces income and profit potential.

Description
Blotchy ripening refers to one or more conditions specific to the external and/or internal color of tomato fruit. Ideally, the skin and flesh color of mature tomato fruit are uniform throughout, with red being most common. Fruit exhibiting blotchy ripening have discolored sections. For example, defected fruits are mostly red on the outside but contain areas that are green, yellow, gray, or paler red than the remainder of the fruit, such as shown in the picture. Blemished areas may be more common on the half of the fruit nearest the stem. The flesh, especially vasculature, of fruit exhibiting blotchy ripening may be brown or broken down.

Symptoms associated with blotchy ripening have underlying physiological, or disease or insect feeding causes. Symptoms can be mild and in only a small number of fruit or severe and/or in many fruit. Regardless, it is important to note that fruit are said to exhibit blotchy ripening only when they are also in the mid-late stages of ripening as determined by changes in firmness and other variables and when insect (e.g., whitefly) and disease (e.g., TMV) are ruled out as causal agents. These two criteria separate truly ‘blotchy’ ripened fruit from firm, immature fruit in the early stages of ripening (which can be mottled in color inside and out) and fruit damaged by the action of pathogens and/or insects. Blotchy ripening is a physiological disorder.

Blotchy ripening has been discussed as a potentially significant marketable yield issue in research and extension publications for nearly ninety years. Seaton and Gray of the Michigan Agricultural Research Station reported on their analysis of the anatomy of blotchy-ripened fruit in 1936. Also, after touring commercial and research farms throughout the U.S., Minges and Sadik of Cornell University published a protocol for evaluating blotchy ripening in 1964 (https://journals.flvc.org/fshs/article/view/100632/96587). These landmark works provided much needed insight on blotchy ripening, and they were followed by other steps that helped identify factors that contribute to the disorder.

Contributing Factors and Prevention

1. Genetics
Immature tomato fruit are green and photosynthetic. Later however, the set of pigments found in fruit of most hybrids shifts and red becomes the dominant color.

This shift is pre-programmed but influenced by conditions surrounding the fruit and within the plant and soil. The first and one of the most reliable steps in minimizing blotchy ripening is selecting varieties known to display it very infrequently – i.e., among few crops year to year and among few fruit within a season.

Hybrid tomato varieties are the culmination of huge, coordinated efforts requiring in-depth knowledge of tomato genes. Nearly 100 years ago, these genes were found to include a natural mutation that led individual fruit to ripen uniformly red, today’s most common standard. Decades of development of varieties whose fruit turn red over their entire surface and throughout their flesh at precisely the right time relative to other variables related to market-readiness have followed. However, the natural condition of NON-uniform reddening remains in the tomato genome and it shows itself most readily in certain varieties. As a category, heirloom varieties may display the blotchy ripening disorder most consistently. As an early step in avoiding blotchy ripening, consult reliable reports on variety performance in your area and select varieties that exhibit the problem rarely, if at all.

2. Environmental Conditions, including Air Temperature, Soil Status, and Nutrient Levels

A variety’s genes may predispose it to physiological disorders like blotchy ripening but this weakness can be minimized or masked with luck and proper management. Factors contributing to the development of physiological disorders like blotchy ripening can be difficult or take a long time to determine because they are difficult to induce experimentally. That said, research and experience have shown that blotchy ripening is most prevalent when air temperatures during mid-late stages of fruit ripening are extreme (e.g., below 60 deg F and/or above 90 deg F) or highly variable, when humidity levels remain high, and/or when these conditions are common and light levels are low. Low soil quality and high salinity are also associated with the occurrence of blotchy ripening.

Most also agree that severe cases of blotchy ripening are most often associated with factors that limit the supply of potassium (especially) and to a lesser extent, magnesium, to maturing fruit. These factors include: waterlogged and/or compacted soils, below-optimal potassium or magnesium application rates, above-optimal nitrogen application rates, excessive application of potassium and magnesium competitors, excessively large or dense canopies, and the environmental conditions mentioned previously.

Potassium supplies may be restricted for different reasons. So, do not over-compensate when evaluating and adjusting irrigation and nutrient management practices. Articles written by Gordon Johnson (University of Delaware), Jerry Brust (University of Maryland), and others are excellent overviews of blotchy ripening and its management. All point to limiting blotchy ripening and similar disorders through careful nutrient and water management, considering soil, plant, and fruit factors in the process.

Limiting the Occurrence and Severity of Blotchy Ripening in Tomato
A. Select resistant varieties.

B. Minimize large temperature swings and extreme high temperatures during fruit development and ripening.

C. Ensure adequate and balanced nutrient levels, paying special attention to potassium and magnesium and their competitors or factors that limit their availability.

D. Maintain consistent and appropriate soil moisture levels.

E. Maintain or improve biological, chemical, and physical characteristics of soils allowing them to support maximum root and plant health.

Prune Fresh Market Tomatoes (field, high tunnel): Yes or No?

Growers and others continue to discuss and ask questions about the pros and cons of pruning fresh market tomato plants in field and high tunnel plantings. Some growers expect to prune and plan for the process while others decide long before planting that they will not prune. For others, the decision is less clear. Regardless, genetic, market, and other factors affect the decision.

Major Factors Affecting the Decision to Prune
1. Variety type (determinate, semi-determinate, indeterminate). Overall, determinate varieties require the least amount of pruning and indeterminate varieties the greatest amount with semi-determinate varieties potentially benefitting from a moderate amount. Whether grafted plants are used, and the effects of the rootstock can also influence if the grower may benefit from pruning them.
2. Variety-specific characteristics. Varieties within each major type differ in how they respond to pruning. Consult reliable sources and use experience to determine if and how much each variety being grown should be pruned.
3. Market price and expectations. Typical market prices and expectations of fruit quality may steer growers to prune or to not prune individual varieties and/or plantings.
4. Pruning process requirements (e.g., time, cost, expertise, materials). Pruning is recommended for some varieties and in some situations. However, if pruning is done incorrectly (wrong time, wrong method), it can result in undesirable outcomes.

Potential benefits and drawbacks associated with pruning field- or high tunnel-grown fresh market tomato plants.

Potential Benefits
• Can enhance earliness
• Can increase fruit quality (e.g., size, shape)
• Can reduce some disease pressure
• Can enhance coverage of protective sprays
Potential Drawbacks
• Adds cost (time, labor) and requires care
• Can spread disease
• Can reduce fruit quality
• Timing is key (crop stage and when foliage is dry)

Fresh market tomato plantings in Ohio differ significantly in size, market, growing environment (field, high tunnel), production system (e.g., organic, not organic), varieties used, and other characteristics. A small-scale test comparing pruned and unpruned plots will help reveal if your current approach is ideal.

For More Information

1. http://www.hort.cornell.edu/expo/proceedings/2015/high-tunnels/BMPs%20Proper%20pruning%20and%20training.pdf
2. http://www.hort.cornell.edu/expo/proceedings/2017/HighTunnel.cherrytomatopruning.ivy.17.pdf
3. https://extension.uga.edu/publications/detail.html?number=B1312&title=commercial-tomato-production-handbook
4. https://extension.okstate.edu/fact-sheets/print-publications/hla/commercial-production-of-fresh-market-tomatoes-hla-6019.pdf
5. https://mwveguide.org/uploads/pdfs/2024-MW-Veg-Guide-full-draft-20231219.pdf
6. https://www.vegetables.bayer.com/au/en-au/resources/growing-tips/agronomic-spotlights/fresh-market-tomato-pruning.html

High Tunnel Crop and Market Period Diversity

High tunnel use is very popular and has been increasing in Ohio and many other states for decades. Growers are now asking new questions partly because high tunnel production is so popular and increasing and has been practiced for so long on some farms, creating new challenges and opportunities.

“How can I utilize my high tunnel(s) more effectively year-round or fall through spring?” is one very frequently asked question. Many agree that spring-fall tomato harvests can offer the greatest revenue or profit potential. However, others have shown or are learning that harvesting other crops from their high tunnel(s) during summer and/or fall through spring can also be lucrative and beneficial in other ways. Many examples of this have been shared in recent Extension and other programs in Ohio and neighboring states. Working with multiple crops across more of or the entire year requires being familiar with conditions affecting their growth, quality, and potential costs of production and market (profit) potential. Labor and other input costs and how one figures costs of production are obvious factors. For example, one grower-speaker at a recent conference recently described high tunnel space on their farm as “rented,” meaning that their costs of production include how much time is required for a crop to be market-ready. This approach (calculation) directs them and, possibly, others: a) to include lower-cost, quicker-cycling, high value crops in their systems, and b) to be selective when devoting space to high value crops demanding more space, time, and labor. For some, producing multiple crops, managing their investments in crops prone to boom-bust supply-price cycles, and accessing markets through most of or the entire is key to their business. They describe how the approach can limit risk and increase opportunity.

As described in our Feb-3 VegNet article, we seeded Mokum carrot, Red Russian kale, Oriole Swiss chard, Red Pac pac choi, and Music garlic in early Oct-2023 and have given them “minimal” care since that time. Our goal was to discover/demonstrate the potential yield and quality of these crops when grown and overwintered in this way, although the kale, Swiss chard, and pac choi were appropriate for some markets in December-January. This approach may interest growers unfamiliar with and/or currently lacking the ability to make large investments in fall through spring production-harvesting. Recent samples taken from the carrot seedings demonstrate that growth is accelerating and roots are likely to be market-ready soon. A large number of other edible and non-edible crops can be overwintered and/or harvested successfully fall-through spring in Ohio.

Please contact Matt Kleinhenz (330.263.3810; kleinhenz.1@osu.edu) for more information.

 

A Minimalist Approach to Ensuring Fall through Spring Vegetable Harvests

Interest in marketing locally-grown, freshly-harvested vegetables fall through spring is strong and increasing among high tunnel growers in the Midwest, Great Lakes, Mid-Atlantic, Mid-South, and Northeast. Scanning the agendas of industry meetings and listening to growers and others in these areas makes clear that fall through spring harvest and marketing of high tunnel-grown crops is an established and increasingly common practice. Importantly, some growers have transitioned to cash cropping their high tunnels only fall through spring and leaving summer to grow cover crops and focus on other priorities, including field-based production. Conversations with and public presentations by these growers and other experts make clear that fall through spring income from high tunnel production can be significant if the correct crops and varieties are chosen and suitable practices are used.

We have long wondered which crops, varieties, and practices may be ideal for Ohio high tunnel growers looking to harvest fall through spring. Much of our previous research focused on a relatively small number of crops and the use of various tools and practices (e.g., films, fabrics, and/or soil heating). Our goal was to describe potential production outcomes when high tunnel growers invested in the process to various levels. Results from those experiments suggest that yields are likely to be greatest when investments are also highest, for example, when soil heating, plastic films, and row covers and the effort to maximize their utility are used. Those studies were summarized previously in this blog.

We are asking a different question in Winter 2023-2024. As the three panels below describe, seven crops were seeded in two high tunnels in October-2023 and grown without any supplemental heating, films, or row covers. This “minimalist” approach explores the worst-case scenario, the minimum that can be expected from these crops under the conditions they have experienced since seeding. This approach may appeal to growers unfamiliar with fall through spring production and/or those who are unwilling or unable to invest much time, money, or effort in it, at least at this time. The test outlined below is one example of what can be expected but many others exist. Of course, different outcomes may be possible when other varieties, planting dates, and growing practices are used. Upcoming evaluations will push the “minimalist” approach further as all crops capable of being grown and harvested fall through spring do not require a high tunnel. Please contact me (Matt Kleinhenz, 330.263.3810, kleinhenz.1@osu.edu) if you would like more information.