This article was written by Dr. Francesca Rotondo.
Bacterial canker (BC), caused by Clavibacter michiganensis, affects both tomato and pepper plants. The disease is seedborne and can be introduced through infected seed or transplants. It spreads through mechanical transmission during pruning and other field or greenhouse operations. The bacterium thrives with high humidity and warm temperatures, and heavy rainfall further contribute to its spread and secondary infections.
In tomatoes, bacterial canker is more severe because the bacterium invades the vascular system. Early symptoms include stunting and wilting, followed by open cankers on the stem. When stems are split open, a thin, reddish-brown discoloration is visible in the vascular tissue, especially at the base and nodes. Secondary symptoms include browning of leaf edges (“firing”), upward curling of leaflets, and small, tan fruit lesions with a white halo, known as “bird’s-eye” spots. (Figure1)
In peppers, the infection is not systemic. It primarily causes foliar symptoms and affects fruit, leading to yield reductions (Figure 2). Canker-infected pepper fields can also serve as sources of inoculum for nearby tomato fields.
Figure 1. Characteristic symptoms caused by bacterial canker in tomato: wilting (A), vascular discoloration (B) and bird-eye lesion on fruit (C
Figure2. Typical symptoms caused by bacterial canker on pepper leaves (A) and fruits (B)
Managing bacterial canker is challenging once it is present. Prevention and sanitation are crucial for an effective management:
• Start with certified and disease-free seeds and transplants
o sanitize seed using hot-water treatment (ohioline.osu.edu/factsheet/hyg-5818).
• Disinfect all tools and equipment to prevent contamination
• Regularly scout for symptoms, and destroy infected plants
• Rotate crops, avoiding tomatoes in infected fields for 3-4 years
• Ensure fields are free of weeds or volunteer tomato plant
• Reduce stresses with balanced nitrogen, improved soil organic matter, and well-drained soil
• Copper fungicides and streptomycin should be applied before transplanting to the field, and copper fungicides can help slow the disease’s progression during the growing season
In 2019 and 2021, the Vegetable Pathology Laboratory (Dr. Sally Miller and Dr. Francesca Rotondo) conducted trials to assess the natural resistance of different pepper varieties (bell pepper, banana, and jalapeño). In 2019, the percentage of marketable fruits was significantly higher in jalapeño and banana varieties compared to bell pepper (80% vs. 60%) (Table1a). In 2021, chili varieties had the highest percentage of marketable fruits (95%), followed by jalapeño (88%), banana (82%), and bell pepper (75%) (Table 1b).
Table 1: results from the field variety trials conducted in 2019(a) and 2021 (b)
In 2021, the Vegetable Pathology Laboratory also evaluated the efficacy of biorational products against bacterial canker in pepper seedlings in two independent greenhouse trials. Theia, Regalia (giant knotweed extract), and Howler reduced BC severity by 78%, 73%, and 68%, respectively, in the first trial. Similar results were observed in the second trial, with Regalia, Howler, Theia, Vacciplant (laminarin), and Stargus (Bacillus amyloliquefaciens F727) reducing disease severity by up to 80% This research was funded by the Ohio Vegetable & Small Fruit Research & Development Program (OVSFRDP).
Following initial detection in Medina County the first week of July, additional confirmations of this pathogen have been made from fields in Wayne, Seneca, and Huron counties, as well as the OSU Extension seminal plot in Wooster. Laboratory diagnosis was conducted by the C. Wayne Ellett Plant and Pest Diagnostic Clinic at the OSU CFAES Wooster Campus. Monitoring continues at OSU sentinel plots in Fremont, Celeryville, and Piketon, with no confirmed detections at the time of writing. Additionally, symptoms consistent with bacterial spot, yellow-vine decline, and bacterial wilt have been observed in the sentinel and nearby plots at OSU research stations across the state, so diligence in insect and disease scouting and management remains imperative.
Heavy sporulation on the underside of a cucumber leaf in Wayne county Sentinel plot F. Rotondo.
Visual foliar symptoms on the upper surface of cucumber leaves from Huron (left) and Wayne (right) counties, F. Rotondo
Microscope view of Cucurbit Downy Mildew, where the individual, lemon-shaped, sporangia can be observed along with sporangiophores, F. Rotondo.
The following information appeared in this newsletter on July 2nd but remains relevant and is reposted for reader convenience.
Growers who have cucumbers and cantaloupe in their fields should take quick action to protect their crop. Cucurbit Downy Mildew is best managed with preventative applications before infection takes place. Once visual symptoms appear, control becomes increasingly difficult and yield reductions may occur. In conditions favorable for disease development, and without effective and timely management, Cucurbit Downy Mildew can cause rapid decline of the plant, severe defoliation and ultimately plant death in just the matter of days. Disease development is favored by rainy, humid conditions (relative humidity greater than 85%) and cooler temperatures ( 60°F to 70°F)
According to research trials completed in Ohio, Michigan, and other states and provinces around the Great Lakes region, the best fungicide options are as follows: Orondis Opti (FRAC 49+M05), Ranman (FRAC 21), Omega (FRAC 29), Previcur Flex (FRAC 28), and Elumin (FRAC 22). These should be tank mixed with chlorothalanil (Bravo, Equus, etc.) or mancozeb (Dithane, Manzate, etc.). Orondis Opti is a premix already containing chlorothalanil, but at a reduced rate. Fungicides have restrictions on how much product can be applied and how often, so follow the label, the label is the law. The more effective fungicides should be rotated to avoid resistance development in the pathogen.
Growers in Ohio should also intensify scouting of cucumbers and melons. Look for yellow or tan angular lesions delimited by veins on the top surface of leaves, and fuzzy grey/brown growth on the undersides of the lesions. With a good hand lens or a smartphone camera with high magnification you may be able to see small dark brown/purple spots within the fuzzy growth. These are the spores of the downy mildew pathogen. You can also utilize the Cucurbit Downy Mildew IPM Pipeline website, where you can sign up for alerts notifying you of nearby confirmed Cucurbit Downy Mildew observations.
If you suspect downy mildew in cucumber or melon please submit samples to the C. Wayne Ellett Plant and Pest Diagnostic Clinic (CWE-PPDC) for confirmation. Instructions for sample submission are here. Please contact Dr. Francesca Rotondo at 330-263-3721 or rotondo.11@osu.edu with any questions. You can also work with your county extension educator to get samples submitted to the lab. A major ‘thank you’ to Dr. Rotondo and her staff in the Plant and Pest Diagnostic Clinic for their critically important work! Also, thanks to financial support from the Ohio Produce Growers and Marketers Association’s Ohio Vegetable and Small Fruit Research and Development Program, there is no fee for this service for Ohio vegetable growers. Please find additional information on Cucurbit Downy Mildew here from OSU and Michigan State
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.
Right now growers are in the final week or two of peak pumpkin sales and events. With production and pest management challenges fresh in your mind, we ask you to consider helping us document your current needs. Ohio State University researchers have been invited to collaborate with other states from the mid-Atlantic to the Northeast on a project to help solve key identified road blocks to production and pest management.
We plan to have a multidisciplinary team of horticulturists, plant pathologists, entomologists, wildlife specialists and extension folks working on this project. Outputs will be focused on applied research trials to solve known issues and produce newsletter articles, factsheets, videos and presentations where progress will be shared.
Please take a few minutes to identify your biggest production and pest management challenges so we can make Ohio needs well represented in the upcoming grant and future project. A summary of the survey results will be posted in VegNet for anyone to review.
Please click the link below to participate; responses will be anonymous and not identified to any grower. Thank you for your time and input.
The OSU Extension Fruit & Vegetable Report is written/published collectively by OSU Extension staff across the state.
View a recording of the OSU Extension Bi-Weekly Fruit & Vegetable Report updates below:
Strip Tillage
Strip tillage is a form of conservation tillage that attempts to combine the benefits of no-till and conventional tillage by working only the area where the crop will be planted. Leaving residue cover over the majority of the field protects the soil against erosion and helps to build organic matter, improve aggregate stability, and boost other indicators of soil health. Working the soil in the strip zone warms the soil faster and prepares a better seedbed to support plant growth.
Components of a strip till unit – A) lead coulter for slicing through residue, B) row cleaners for parting residue, C) shank for fracturing and lifting soil, D) berm-building coulters to shape tilled soil into strip, & E) rolling basket for creating level seedbed. Photo courtesy of Orthsman/Unverferth Manufacturing.
Strip-till in sweet corn stubble. Photo by Chris Galbraith, OSU Extension.
While strip till targets the benefits that come with integrating the two systems, there are downsides to consider as well. These mostly involve issues with cover crop and/or residue interference with growing the crop. Vigorous cover crops need to be terminated in a timely fashion and crop development can still be delayed in strip-till if the season begins cold and wet. Pests like slugs and voles can also build-up with the increased residue cover. The cost of the equipment can also be a substantial investment which creates a barrier to entry for many growers.
Many vegetables can be grown in strip tillage systems, including cucurbits, sweet corn, snap beans, potatoes, cole crops, carrots, and more. Recent studies at Michigan State University have found a slight yield increase from strip till in vegetable crops, but many of the issues mentioned can impact this (climate, residue management, pest pressure). It is important to consider the factors that go into making strip till a successful venture in order to make the most of the equipment and the practice.
This season has been severe in terms of wildlife damage in specialty crops. Animals like deer, groundhogs, voles, raccoons, and birds have caused major losses on some farms. Dr. Marne Titchnell, wildlife program director for OSU Extension, recently gave an in-depth presentation at Farm Science Review on different wildlife mitigation strategies for growers. The information and slides can be found on her blog through the link below:
Opportunities abound for farms when it comes to teaming up to save money and improve effectiveness through joint purchasing, collaborative marketing, and other similar practices. These types of partnerships between farm businesses is captured by the cooperative or “co-op” model where growers access resources and savings by acting together and making decisions as a group in certain scenarios. The Center for Cooperatives at OSU specializes in these sorts of opportunities and can offer guidance to growers who are interested in leveraging the benefits of organizing for collaborative business purposes.
Heavy cross striped cabbageworm and imported cabbageworm feeding is still being observed in some brassica plantings. Aphids have made a late season push in brussel sprouts, cabbage, cauliflower and broccoli plantings. Cabbage aphids are typically a grayish color, and are often found amongst a waxy, white secretion which covers their body. Reproduction rates of these aphids are highest in temperatures between 50-68F. Scout for these pests on the underside of younger leaves, between leaf layers and on flower buds or seed stalks. It is recommended to treat cabbage when you see 1-2% of plants infested with aphids. There are a number of products that can be used to treat aphids in cabbage including Movento, Sivanto, Assail, Exirel and Beleaf. Prioritize products that have reduced toxicity (e.g., Beleaf) which will conserve natural enemy communities. Refer to the Midwest Vegetable production guide for other options.
Cabbage aphid infestation. Photo by Frank Becker, OSU Extension.
Cucurbits
Cucurbits are seeing upticks in a variety of beetles in flowers and fruit. These include corn rootworm species. Spotted cucumber beetles are active. Aphids are also beginning to be found with some more frequency in the fall vine crops. Squash bugs are also active within the crop. Most cucurbits do not have blooms in fields, so pyrethroid and carbamate applications may be applied (e.g., Sevin, Pounce, Capture). Refer to the Midwest Vegetable production guide for other options.
The pumpkin crop has been strong in Ohio this season. Many growers in northwest Ohio were able to manage downy mildew with fungicides. Plectosporium blight has been causing some problems for growers where fungicide spray coverage may not have been as thorough as desired. Most fungicide spray programs being used are adequate to limit impacts from plectosporium blight. Spray penetration into the canopy and coverage across the field is as important as selecting the right product.
Plectosporium blight on pumpkin, identified by light colored lesions on fruit, handles, and vines. Photos by Frank Becker, OSU Extension.
Fruiting Vegetables
Late blight has been confirmed in several tomato fields in and around Wayne County. Bacterial diseases have also begun to start, and with cool mornings and heavy dews, it will become increasingly more difficult to manage.
Several high tunnel producers have reported dealing with broad mites/cyclamen mites in their high tunnel peppers. The mites feed on the fruit while it is still developing and their feeding damage causes the peppers to become russested and misshapen. The leaves may also appear distorted, almost as if they were drifted with herbicides. Keep in mind that these mites are in a different group than two-spotted spider mites. Therefore, it’s important to select control options that are appropriate and effective on this species. Sanitation and crop rotation are also important cultural control measures that need to be taken when dealing with mites in high tunnels.
Onions
Although the growing season is behind us for onions, curing is still ongoing, and some growers have reported some challenges with curing. Make sure that you are providing the proper conditions for curing onions. Less than ideal conditions will result in frustrations and losses of product. Ideal conditions are warm, dry, well ventilated areas. Ideal temperature range is between 75-90F. The other factor that contributes to losses while curing is not curing the best graded onions. Curing is not an attempt to bring quality back, only preserve it. Grading hard for only the best onions to be cured will help reduce the chance that rots begin to develop. Take note of any disease or insect issues that you have observed this year and use these notes to help you next year. Onions that may have had heavy thrips loads, or untreated disease infection during the season are not going to hold up as well as desired during the curing process.
Green onions are seeing thrips populations slow down. Typically, thrips populations will decrease as we enter into Autumn and see these species move onto weedy hosts.
Fruit
Sanitation is an important component of an integrated disease management program. In small fruit and tree fruit alike, there are diseases that can over winter on infested fruit, foliage and branches. As the season winds down, it is still important to scout for diseases that may be present, identify the disease and have a plan of action to manage the disease. Finding and removing mummy fruit, which are dried and shriveled fruit that are typically full of fungal structures, will help to significantly reduce disease inoculum from the production area. Too, mowing and mulching or raking away the leaves from around the trees and bushes reduces the amount of viable inoculum that may be overwintering in foliage. Much progress can be made towards disease management with efforts made in the fall. Taking these steps, and committing to them long term, helps to break disease cycles and reduce the overall pathogen load over time.
Fruit rots are being observed in apples, including white rot and bitter rot. Bitter rot is common in apples during warm, wet conditions. For more information, take a look at this OSU article on bitter rot in apple. Marsoninna blotch is also found on apples.
The pawpaw crop in Ohio this season has been later and smaller than past years. Pawpaw is a niche crop that is gaining popularity with Ohio consumers and can be used as an ingredient in specialty craft beers, ice cream, and other value-added items. For more information on pawpaw production, check out this factsheet from Cornell University. Learn more about the pawpaw industry in Ohio by visiting the Ohio PawPaw Growers Association website.
Pawpaw fruit cluster. Photo by Clemson University.
This article is provided by Chris Galbraith, MSU/OSU Extension & Jenna Falor, MSU Extension.
Late-season weed management is essential to consider when developing a weed control plan for your operation. Despite one’s best efforts, weeds can often escape early-season control. This can be a result of poor timing, missing the plants with cultivation, spray applications or flaming, or due to herbicide resistance. If allowed to reach reproductive maturity, escaped weeds can cause management problems in future years due to replenishment of the weed seedbank. These larger weeds can also harbor crop pests and diseases, interfere with harvest by obstructing equipment, or degrade final crop quality through contamination from weed residues.
Management practices for escaped weeds are notoriously limited due to the difficulty of controlling weeds when they have reached a significant size. Weed wipers use an applicator made of an absorbent material, such as sponge or a rope wick, that is saturated with herbicide and used to contact weeds growing above the crop canopy, killing the weeds but leaving the crop unaffected. The downsides of this method include a lack of herbicide options effective on larger weeds, limited efficacy on herbicide-resistant populations (depending on what product is being applied), and its unsuitability for use in organic systems. Another option is sending in hand weeding crews to manually weed the fields, which is particularly common for managing escaped weeds in vegetable production. While this method does tend to be effective, the labor is expensive, time-consuming, and hard monotonous work for employees.
The major manufacturer and supplier of electrical weeding equipment in the United States is The Weed Zapper, a Missouri-based company that began production in 2017. Electrical weed control technology has also been developed by the Brazilian company Zasso and the European companies AgXtend, Rootwave, and Crop.Zone. While electrical weeders from foreign companies are as of yet rare in the U.S., familiarizing oneself with the technology that has been developed overseas shows the versatility of this technology in different cropping systems and gives a clue as to the future of the equipment in modern agriculture.
Pro-environmental attributes of the equipment are that it does not disturb the soil and does not require the use of any chemical herbicides. Electrical weeding provides systemic control of even larger plants, making it an effective option for controlling weed seed bank inputs by terminating weeds at or prior to reproductive maturity. Similar to mechanical weeding and certain herbicides, it is non-selective and therefore caution must be taken to prevent crop injury. This typically restricts in-season use to crops with low-canopy growth habits that don’t come into the path of the electrode. While this limits the application of electrical weeding, there still remains many crops where growers might benefit from integrating this equipment into their weed control plan.
Jim Jasinski (OSU Extension), Chia Lin & Reed Johnson (OSU Entomology), Hongmei Li-Byarlay (Central State University)
Brassica cover crops like mustard (Brassica juncea) and rapeseed (Brassica napus) can be a good fit in some production systems, providing a range of benefits such as soil health, soil biofumigation and pollinator health.
Blooming mustard crop.
Recently it was reported that the natural biocides (glucosinolate compounds) produced by mustard plants could mitigate infections of Nosema (a fungal parasite) in honey bee colonies. If glucosinolates are present in mustard pollen, mustard blossoms may provide the dual benefits of food source and disease control for honey bees.
To test that hypothesis, a two-year multi-site research project led by Dr. Chia Lin was recently funded to look at the effects of spring (mid-April) and late summer (late July) planted mustard as a cover crop to provide abundant pollen to foraging bees in order to measure specific effects on colony health. Both lab and field studies will be used to identify how much mustard pollen is collected by the bees and beneficial aspects of the targeted mustard planting on reducing Nosema impact on honey bees and improving winter survival of bee colonies. Stay tuned for updates on this project.
Mustard cover crop emerging from one of the research sites.
Delta style Trapview trap in apple orchard with solar charger, humidity sensor and antennae.
Jim Jasinski, Frank Becker (Extension); Ashley Leach (Entomology)
Well, not quite HAL from 2001: A Space Odyssey. The Ohio State University IPM Program and Department of Entomology have maintained an insect pest monitoring network for over three decades. Typically, pests are monitored using either sticky traps, scent-based traps or pheromone traps.
As trapping technology has evolved, OSU is now experimenting with Trapview camera traps that purport to identify pests captured internally on sticky film using Artificial Intelligence (AI) software. Each AI identified pest is then reviewed and verified by a trained employee for accuracy. While the camera based traps are relatively expensive compared to traditional monitoring traps ($650 apiece), they require very little maintenance except pheromone lure replacement. The cost savings will come from time saved physically inspecting the trap every few days or weekly throughout the season. The number of pests identified by the AI is tallied per day and shown on a website and app, along with a picture of the pests on the sticky panel inside the trap.
Through a grant from Ohio Vegetable and Small Fruit Research and Development Program, five Trapview traps will be evaluated at three locations (Wooster (3), Celeryville (1), South Charleston (1)) on three different pests (Corn earworm (2), Grape berry moth (1), Codling moth (2)) compared to the standard trap for each pest. Updates on how well these AI based traps compare to standard traps will be reported at various times throughout the season.
Image capture inside Trapview trap. Insects caught are non-targets, otherwise they would be highlighted by green box indicating positive ID.
Plant biostimulants are a large, diverse, popular, and enigmatic category of inputs. Many growers rely on them while others are skeptical. Most agree that more farmer-friendly information is needed to help ensure growers receive consistent and adequate returns on their investments in plant biostimulants. Click on the “video seed” below to refresh your understanding of plant biostimulants or help become more familiar with them as you consider their possible role on your farm.
Join Holden Arboretum’s Natural Areas Biologist Rebecah Troutman to learn more about a newly discovered enemy of the invasive garlic mustard. This webinar will teach participants how to find and identify Liaphis alliariae, a garlic mustard specialist aphid native to Europe. This aphid was found during the 2021 field season. Affected plants produced twisted seed pods and puckered/wilted leaves. Given the importance of controlling garlic mustard, the novel nature of the newly discovered aphid in the United States, we are trying to better understand the impact this species has on garlic mustard- could it be a desperately needed biocontrol agent? The objective is to quantify the impact of this novel aphid on garlic mustard and map its current distribution.
