Root-knot nematode galls on tomato
As the vegetable growing season winds down, now is a good time to dig up plants in high tunnels and open fields and determine the health of the roots. Root diseases that may not kill plants outright can nonetheless stunt plant growth and reduce yields. Look for plants that appear less vigorous than others and remove them with a shovel, taking care to maintain root integrity. Shake off the soil and rinse the roots gently with water. Then examine roots for symptoms.
While some soilborne diseases such as Phytophthora blight can “explode” in the field from relatively low initial inoculum levels, many others build up slowly from season to season. Root-knot, caused by the the plant pathogenic nematode Meloidogyne spp., is increasing in prevalence in Ohio in high tunnel tomatoes and other crops in open fields. Root-knot is fairly easy to identify – galls are clearly visible on roots. The Northern root-knot nematode, which predominates in northern Ohio, causes small galls, while the southern species, which occurs in southern Ohio, causes large galls. Since root-knot nematodes have a very broad host range, crop rotation may not be helpful, although certain cover crops such as sudangrass are toxic to nematodes, and wheat and corn are not hosts of northern root-knot nematodes. Anaerobic soil disinfestation (ASD) is highly effective against root-knot.
Corky root rot of tomatoes
End-of-season root health checks are especially important for high tunnel tomatoes, which are often produced in the same soil year after year. Root-knot, Verticillium wilt, corky root rot, black dot root rot, and Pythium root rot are among the root diseases that can predominate in long-term non-rotated tomatoes. The roots should be evaluated every year to assess disease development and the need for control measures such as grafting on disease-resistant rootstocks and ASD. A fact sheet describing tomato soil borne diseases and their management can be found here.
“Specialty” — as it applies to vegetable varieties – usually refers to ones differing in at least one noticeable way from the mainstream version of the crop preferred or expected by most buyers. That difference can be in size, shape, color, flavor, texture, and/or other characteristics. Oftentimes, specialty varieties are initially grown specifically to attract or meet the stated interest of buyers looking for “something different from what they can get everywhere else” and willing to pay higher prices for it. In a small number of cases, markets for specialty varieties increase to the point that the specialty designation or perception falls away, i.e., the variety is so widely grown that it resets what is considered normal or mainstream, but that process can require years to complete. The opposite can occur, too, as markets for individual specialty varieties can remain small and fade quickly. In any case, when grown and marketed well to a sufficiently large number of buyers, even if local, specialty variety production can be profitable. Well documented cases of specialty vegetable and variety production being significant for many growers on both coasts and within easy reach of urban areas in states between them fill the extension, research, and industry literature. Some growers are, more or less, always searching for the next unusual variety that will help set their farm apart.
A variety just being different is not enough to attract and maintain the interest of most buyers. The difference must be meaningful. In the well-chronicled case of ‘Honeynut’ squash (e.g., see https://www.bonappetit.com/story/honeynut-squash-history), the most meaningful difference may be size since ‘Honeynut’ is positioned as a mini-butternut. Its small size makes ‘Honeynut’ more versatile and appealing to buyers looking for the culinary/dietary benefits of butternut fruit but in a smaller package.
We included ‘Honeynut’ squash in two experiments in 2019, planting it in the same rows as ‘Metro PMR’. ‘Honeynut’ was used as the “spacer” between plots of ‘Metro PMR’, the actual focus of the experiments, both of which were managed organically. However, observing ‘Honeynut’ during the season and completing informal eating quality assessments, its appeal is clear. ‘Honeynut’ serves as a reminder of the benefit of considering alternative varieties, especially as the period for selecting varieties and ordering seed for 2020 gets underway.
Fall armyworm and beet armyworm are two pests that we monitor with pheromone traps throughout the summer at several sites in Ohio. These two pests are sporadic in occurrence; they are sometimes absent in Ohio and sometimes present at damaging levels, especially in September and October. These were absent for most of this summer at Ohio sites, but are present now at some sites.
Fall armyworm attacks sweet corn, peppers, and tomatoes. This year, the fall armyworm was detected in Huron County, Medina County, and Franklin County starting in late August, and it is still being detected at those locations.
The beet armyworm has been absent at most sites but has been detected during the past week in Franklin County. It attacks peppers and tomatoes.
These two pests are challenging to manage because their appearance is so sporadic and because the larvae are generally tolerant of pyrethroids; they are better controlled by non-pyrethroids such as Avaunt, Proclaim, Radiant, or Intrepid.
Corn earworm is a third pest that is best known as a significant pest on sweet corn in late August and into September, but once the sweet corn is gone, the corn earworm can cause significant damage to bell peppers. It also attacks tomatoes where it prefers green fruit over red fruit. Corn earworm moths were detected at very high levels in late August at some sites, and they are still being detected at high density in Clark, Franklin, and Huron Counties.
-Celeste Welty, Extension Entomologist
Downy mildew was found this week in organic pumpkins in Harrison County. Options for downy mildew control are limited in organic cucurbits, and at this point in the growing season the damage may not significantly affect yield. Downy mildew affects pumpkin leaves but not vines or fruit. The main danger, once fruits have matured, is defoliation and subsequent sunburn of the fruit. If plants are defoliated, and sunny weather is expected, fruits should be removed from the field and stored in the shade.
Previously this summer we found downy mildew on cucumbers and cantaloupes in our sentinel plots and on commercial farms. The disease appeared on cucumbers/melons much later in the growing season than expected, first detected on August 22. The strain of the downy mildew pathogen that appears early, usually in early July, is thought to originate in greenhouses in the Great Lakes region. This strain only affects cucumbers and melons, and we don’t know why the early introductions did not happen this year. The strain that infects all cucurbits originates in the South, always arrives in August or later, and is likely the main culprit this year. We are currently testing isolates to identify the strain type from plants we’ve collected in Ohio.
From a buyer’s point of view, many characteristics contribute to pepper fruit quality. Quickly and at all points along the chain from farm to plate, quality is assessed based on a lengthy list of fruit characteristics (e.g., size, shape, color, weight, wall thickness, taste, texture) and using one or more of the senses and/or various instruments and technologies. Although most consumers expect high-quality versions of individual types of peppers (e.g., bell, habanero) to have specific sets of characteristics, others look for “new” or “different” versions of familiar crops and are often willing to pay more for them. With that and other important production-related considerations in mind, research at The OSU-OARDC is evaluating the effects of physically hybridizing different types of pepper plants – i.e., using bell, habanero, and other types of pepper as rootstock and scion during grafting. Varieties of different types of pepper are known for their vigor, maturity, disease and abiotic stress tolerance, and fruit size, shape, color, texture, taste (including “hotness”), etc. As with all other vegetable crops that are routinely grafted (tomato, eggplant, watermelon, cucumber, cantaloupe), plants and fruit resulting from combinations of pepper varieties made through grafting are being tested to determine if they provide growers with advantages so far unavailable from standard variety development. Grafted plants within this group were prepared months ago and include bell and “hot” varieties as rootstock or scion. When healed, the grafted plants and their ungrafted comparison plants were placed in containers in an outside growing area and managed using standard approaches. On Sept. 21, the plants were moved into a greenhouse so that fruit development could proceed more reliably, given the date. Going forward, fruit they produce will be examined in the laboratory, including for their level of capsaicin and relative “hotness”, in a process led by Dr. Joe Scheerens. Grafted and ungrafted versions of tomato and watermelon plants and fruit they have produced are being studied in four other large-scale field experiments also now moving into their laboratory and data analysis stage. Reports from these and other experiments will be issued throughout the fall-winter but Matt Kleinhenz can be reached for more information in the meantime.
As of Monday, most reports of downy mildew in our neighboring states – MI, KY, PA – were in cucumbers, as were our previous reports. However, we found downy mildew on acorn squash in our sentinel plot on the OSU North Central Agricultural Experiment Station in Sandusky County and on cantaloupe in our sentinel plot on the OSU Muck Crops Experiment Station in Huron County. While we have not had reports from most Ohio counties, it is likely that downy mildew is widespread in Ohio. Now we have evidence that the strain that infects most cucurbits, including squash and pumpkins, is present here. The cucurbit growing season is winding down, but if cucurbit crops are expected to be in the field in the next few weeks they should be protected with fungicides. See my blog post on August 22 below for fungicide recommendations.
The downy mildew pathogen does not infect cucurbit fruits but if plants are defoliated the fruits are at risk of sunburn. Sunburn may not be obvious immediately in the field but may develop in storage. In fields with significant defoliation, pumpkins and winter squash should be removed from the field and into shade for curing.
Finally, the downy mildew pathogen does not survive over the winter in the absence of living cucurbit plants. However once harvesting is completed, plants should be disked as soon as possible to kill remaining green tissues that may otherwise be infected and serve as sources of inoculum. This will reduce downy mildew inoculum that can spread to cucurbit crops near and far.
Do you have a bird problem on your farm? Do you want to encourage beneficial birds as an IPM tool? If so, consider attending this free webinar. Registration information below:
Webinar: Supporting Beneficial Birds and Managing Pest Birds
Supporting Beneficial Birds and Managing Pest Birds
Join eOrganic for the first webinar of our fall season! The topic is Supporting Beneficial Birds and Managing Pest Birds, by Jo Ann Baumgartner of the Wild Farm Alliance, Sara Kross of Columbia University, and Sacha Heath of the Living Earth Collaborative.
Beneficial birds can help farmers keep pest insects, rodents, and pest birds at bay. They act the same way that beneficial insects do in helping with pest control. The overwhelming majority of songbirds are beneficial during nesting season because they feed pest insects to their voracious nestlings. Farmers may be able to reduce their pest-control costs by providing habitat for these beneficial birds and by only targeting detrimental birds at the right time and place. Wild Farm Alliance and two avian ecologists will present on: a) How birds’ diets, foraging strategies, and nesting periods affect the farm, b) How best to manage and co-exist with pest birds, c) Why on-farm habitat and the surrounding landscape influences pest control, and, d) What farmers can do to make farms more bird-friendly and resilient. With this webinar and the associated Supporting Beneficial Birds and Managing Pest Birds booklet, we aim to help all farmers and farm consultants make the most of birds on farms.
About 10 days ago we harvested a few pumpkin trials at the research station. After weighing and grading the fruit, they were set back in the row but not in the leaf canopy. Last week I drove by some of the plots and noticed some fruit were sunburned. Such is the fate of many pumpkin fruit exposed to direct sun and not covered by leaf canopy. Sunburned fruit have a reddish area facing the sun which will eventually soften and rot.
Reddish area on near fruit, sunburn.
Over the year’s growers have asked me, how long into the season should they treat the foliage with fungicides? I would respond as long as you plan to harvest fruit. Avoiding sunburned fruit is the primary reason to keep the foliage healthy later into the season. Given our increasingly warmer and sunnier fall season, growers should expect to incur significant losses if the foliage is degraded by bacterial or fungal pathogens.
Conditions that favor sunburn include thin leaf canopies, fruit that have been clipped off of the vine but left in the field to cure or be packed at a later date, and clear sunny days with highs above 80-85F. The weather forecast for the next week in southwest Ohio include max temperatures in the mid 80’s to low 90’s…let’s hope periodic cloud cover spares growers from excessive fruit losses.
As detailed in VegNet on 24 August, we have seen very high numbers of corn earworm moths caught in pheromone traps since mid-August. Trap catch remained very high last week at most Ohio sites where we have traps. This pest prefers to lay its eggs on fresh-silking sweet corn but also can cause significant damage to tomatoes and bell peppers.
Our Ohio trap reports for corn earworm and several other vegetable pests are posted online, at this link: https://docs.google.com/spreadsheets/d/10gh3rHahdxLKkXQapGyEPxWsjHYRmgsezOoFHnwtyEo/edit?usp=sharing
One of the details shown on our trap report page is the type of trap. At most of our sites, we are using the type of trap called a Scentry Heliothis trap, which is a large cone-shaped trap made of white nylon mesh. At two of our sites, South Charleston and Columbus, we have the type of trap called a Hartstack or Texas Cone trap, which is the same shape but larger and made of metal hardware cloth. The Hartstack trap tends to catch much higher numbers of corn earworm moths, and tends to detect low density populations of corn earworm more effectively than the Scentry Heliothis trap. The Hartstack trap is not readily available from trap supply companies, thus we recommend the Scentry Heliothis trap to our cooperators. However for anyone who is interested in Hartstack traps, here are two tips. The plans for making your own Hartstack trap are shown in a fact sheet from Kentucky: https://entomology.ca.uky.edu/ef010 . We purchased our Hartstacks several years ago from a source in Illinois (see http://www.agrinews-pubs.com/news/building-a-better-bug-trap/article_c69e27e7-fa1e-58b5-b5f7-442112bfb2a0.html )
-Celeste Welty, Extension Entomologist