This edition of the OSU Extension Fruit & Vegetable Report was written using field observations and expertise from the following OSU Extension staff: Frank Becker, Thomas Becker, Chris Galbraith, Matt Kleinhenz, Ashley Leach, Carri Jagger, James Jasinski, Logan Minter, & Francesca Rotondo. 

Vegetables

Much needed rain has fallen across parts of Ohio to alleviate the dry weather – too much in some areas, which has caused standing water in fields that has harmed some plantings. This provides a good opportunity to discuss how to treat produce that may come into contact with floodwaters. 

One thing that might be good to clarify up front is the difference between floodwaters and pooling. Pooling occurs when there is a depression in the topography of the land where irrigation or rain water may collect. Standing water from pooling is not considered to be high-risk with regard to produce safety. Flood water comes from water that is flowing or overflowing from heavy rain events that may pick up contaminants and other things as it moves across the landscape. These contaminants include, but are not limited to bacteria, molds, human and animal waste, fungi, and other pathogens. Not only could these contaminants lead to rot issues in produce, there is also a significant food safety concern with produce that comes into contact with floodwaters. Any produce that comes into contact with floodwaters should not enter the food chain. If there are any questions or uncertainty, you can do a risk assessment of your flooded field. More information on flood risks and conducting a risk assessment can be found in this fact sheet on Ohioline: https://ohioline.osu.edu/factsheet/anr-27 

Necrosis beginning along leaf edges is one symptom of bacterial canker in tomato. Photo source: Dan Egel, Purdue University.

Bacterial diseases are still being reported, including bacterial canker in peppers and tomatoes. Reports of severe feeding from cucumber beetles and squash bugs is ongoing – some squash varieties such as Taybelle seem to be particularly attractive to these insect pests. Populations of spider mites and brown marmorated stink bug have seen an uptick. According the the recent OSU C.O.R.N newsletter, trap counts for the sweet corn caterpillar pests corn earworm and western bean cutworm are fairly low across the state at this time.

Late blight has been confirmed in tomatoes in Western New York and Western Pennsylvania. Now is a critical time to be scouting for late blight in potatoes and tomatoes. You can utilize the University of Wisconsin late blight disease risk model for the upper Midwest to help determine if conditions have been favorable for disease to occur. This model can also be used for several other disease and pest issues in our area. 

Example of a late blight lesion on potato foliage. Photo Source: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org

Fruit

Educators are trapping for spotted wing drosophila (SWD) in blackberries and other small fruits. Populations were high and have only dropped off just recently. During periods of high SWD trap catches, it can be beneficial to do a salt test to get a sense of the level of infestation. You can conduct a salt test by placing a number of fruit in a small container with some water and salt. It can help to mash the berries a bit to help coax out any SWD larvae. Any larvae that were in the berries should be drawn out and will float to the surface of the water. A salt test can help growers determine how effective their pest management program is compared to just going off of trap counts. With SWD, we will likely see decent numbers in traps once they are present throughout the season. High trap counts can be alarming, but aren’t always what we want to base the success of our spray programs on. The salt test can help us see if we are managing populations enough to prevent berries from becoming infested with larvae. If we don’t see any larvae after conducting a salt test, this could be a good indicator that our pest management program is effective.  

Anthracnose crown rot has been confirmed on the crown and runners of strawberries. Anthracnose is a fungal disease caused by several species of Colletotrichum. Crown rot of strawberries is typically the result of infection by Colletotrichum fragariae. Mild winters have allowed for continued northward expansion of this disease. Accordingly, we have continued to see an increased impact on strawberry plants, with losses due to anthracnose crown rot. In an OSU Fact Sheet written by Mike Ellis and Omer Erincik (PLPATH-FRU-16), several strategies are recommended for prevention and management. First, it is important to start off with disease-free plants. It is also important to irrigate correctly, reducing overhead irrigation if possible, but also providing moisture to plants after harvest to prevent stress on the plant from excessively dry conditions. Mulching can also help reduce disease incidence by reducing soil splash. If you have infected plants, remove them from the planting, including berries and as much of the plant as possible. Weed control can also be impactful in reducing disease inoculum as several weed species can serve as alternative hosts for this disease. Overall, sanitation is highly important for successful prevention and management of anthracnose in strawberries. 

Excess fertility and heat caused fruit abortion in strawberries and other small fruit. It is recommended across all crop types that fertilization is not done during times when plants are under heat and drought stress. Not only can this burn and stress plants, but without adequate soil moisture, the nutrients applied will not be available for uptake via the root system. There needs to be moisture available to allow for the nutrients to enter the soil solution and move into the roots through mass flow.  

Dr. Ashley Leach, Assistant Professor of Specialty Crop Entomology with OSU, has provided the comprehensive fruit insect pest update below, including figures and tables:

Stink bugs are here. Some sites with large influxes (>20/bugs per trap). BUT, most sites have only a few bugs (0-3 bugs/trap). Codling moth counts are lower, but not at zero. Oriental fruit moth is hitting its third generation throughout the state – treat if you catch >8 moths/trap. Mite and aphid populations are pretty low this week. We noticed a HUGE natural enemy population with lots of “good” guys (ladybugs, lacewings and minute pirate bugs).

For those of you near the Northeast side of the state or receiving bins from the Mid-Atlantic, watch out for Spotted Lanternfly. This new invasive insect has a limited impact on tree fruit, but will harm grape.

**These updates include NEWA weather modeling which estimates insect development based on growing degree days. If you’re interested in how that works, you can follow this link: https://newa.cornell.edu/crop-and-pest-management. **

As mentioned, stink bugs (Brown marmorated stink bug and green stink bugs) are present in orchards. If you see an influx, consider one of the products in the table below, but apply sparingly since certain products will make mites and aphids worse (below).

Mites seem to be held in check recently. If needed, consult the miticide chart below. Make sure to take the product efficacy into account (****=best control,***= good control, **=fair control, *=poor control).

Oriental Fruit Moth is in its 3rd generation in the south – applications may be needed in higher pressure areas. Options for applications are in the chart below. Make sure to take the product efficacy into account (****=best control,***= good control, **=fair control, *=poor control).

Codling Moth –  If treating the second generation, rotate insecticides to feature a different active (IRAC code) than what you sprayed in May. If facing high pressure, >5 moths/trap, make additional insecticide applications. Some options are also included in the chart below.

As a reminder, be sure to always consult your pesticide label and regional pest management guides.

For more information or if you have questions, please reach out to a member of the Fruit & Vegetable team or your county extension educator.

This edition of the OSU Extension Fruit & Vegetable Report was written using field observations and expertise from the following OSU Extension staff: Frank Becker, Thomas Becker, Chris Galbraith, Gary Gao, Melanie Ivey, Carri Jagger, Dan Lima, Diane Miller, Francesca Rotondo, Ryan Slaughter

Vegetables

Tobacco hornworm. Photo by Ryan Slaughter, OSU Extension.

Hot, humid conditions have brought upon bacterial diseases in fruiting vegetables. Management of bacterial diseases can be challenging and frustrating. Foliar bacterial diseases are best managed with an integrated approach of sanitation, selection for disease resistance, and application of effective bactericides. There are 2 main groups of bacteria that cause diseases in plants, and they are Pseudomonas and Xanthomonas. Pseudomonas has a favorable temperature range of 60-75 degrees fahrenheit. Xanthomonas has a favorable temperature range of 77-86 degrees fahrenheit. Once present on the plant, the bacterial infection may appear to be inactive during periods of unfavorable conditions, however, the infections become active again when conducive environmental conditions return. 

Symptoms of bacterial disease present on leaves and fruit of tomato. Photos by Frank Becker, OSU Extension.

Bacteria can be easily spread via splashing rain, plant to plant contact, human activity, insect activity and on equipment. It is critically important to properly diagnose foliar lesions observed in your crops to allow you to take proper care and precaution, especially if the disease is found to be bacterial. Aside from using clean seed and following proper sanitation practices and other cultural crop management recommendations, utilizing chemical control products such as copper, mancozeb, certain botanical oils and Bacillus species can help to combat bacterial infections. Always read the label to ensure that the product that you are considering using has activity against bacterial pathogens. 

Pith necrosis, also a bacterial disease, has been observed in tomatoes. The only strategy for managing pith necrosis is prevention by avoiding favorable conditions, in particular excessive nitrogen. Copper fungicides are not able to provide control because this soil-borne bacterial pathogen is inside the plant.

Fungal diseases are also being reported, including Septoria leaf spot in tomatoes and Alternaria in melons. Downy mildew (clade 2 that affects cucumber and cantaloupe) has been found in at least five Ohio counties to date. Samples with yellow vine decline and bacterial wilt have been coming into the diagnostic lab. A reminder that when sending samples into the lab, make sure to include the full plant with roots if possible.

The 2nd generation of flea beetles continues to cause trouble in young cole crops. Spider mites are also seeing an uptick with the recent scorching weather. Corn leaf aphids are being observed around the Great Lakes region, affecting mostly sweet corn.

Corn leaf aphids on sweet corn tassel. Photo by Chris Galbraith, OSU Extension.

It’s getting to be that time of the year where we might have some of our early crops reaching the end of their productivity. Whether it’s cucurbits or cole crops or anything that we got planted early, we are now left with trying to figure out what to do with this now unproductive space in our field or garden. You have a couple of options:

Succession Planting: You may decide that you really don’t want to be done with growing something just yet. You could consider succession planting. Succession planting is a way for you to grow a crop throughout more of the growing season, instead of, for example, just growing a cool-season crop in the spring and being done for the rest of the season or waiting until you can plant warm-season crops and only having the one crop for the season. In the right circumstances, you could have an early cool-season crop, followed by a warm-season crop, followed by another cool-season crop depending on the amount of time it takes each crop to reach maturity. For example, you might plant something like lettuce or radishes early in the spring, then after you have harvested that crop, you might come in and plant something like beans, tomatoes, peppers, etc.

Done for the season: Maybe you are done planting new crops for the season, and that’s just fine! There are some best management practices though we can implement to make sure we are keeping our other crops protected and healthy. If you have a crop that is done producing, and perhaps starting to senesce, it is best to remove that plant material from the garden or field. Even though you might be done with the plants, pests and diseases certainly are not. If left in the garden or the field, this plant material can serve as a harborage for pests and diseases that could still impact our crops that are still growing. Removing this plant material gets rid of a favorable environment for things that would otherwise pose a threat to the rest of our garden or field. You can either physically remove the plant material and burn it or compost it, or you could work it into the garden or field to bury the plant material. 

So, whether you are done with an area in your garden or field or if you plan to keep planting, don’t just leave all that plant material behind. End of season best management practices can set us up for success for the rest of this season and for the next growing season! 

Fruit

Hot and dry weather has continued to promote population development of European red mites and two-spotted spider mites. This problem can be made worse with applications of certain insecticides that wipe out beneficial insects and natural enemies that would otherwise be keeping the mite population in check. Codling moth and oriental fruit moth seem to be slowing down in eastern Ohio.

Strange spots were observed on apple across the Great Lakes region. Some cases from other states have been confirmed as blister spot (Pseudomonas). Blister spot tends to occur more frequently in cool, wet weather which has not been characteristic of the season in much of Ohio. The apple variety Mutsu is particularly susceptible to blister spot. Ohio cases were not found to be bacterial in nature – final diagnosis concluded the symptoms were likely due to spray injury that occurred during recent high temperatures. 

Blister spot in apple. Photo source: John Hartman, University of Kentucky, Bugwood.org.

Some apple trees this year were observed to have “mummy” fruit that didn’t size up and develop properly but still remained on the tree. MaxCel, a plant growth regulator used for thinning, seems to cause this issue in some years with different varieties. Going back through to hand-thin is too labor intensive and so growers often resort to having workers  just harvest around the undeveloped fruit.

The hot weather has also resulted in sunscald concerns in small fruit and orchards. Once sunscald occurs, the fruit can become susceptible to other pathogens and secondary pests. 

Strawberry foliar and crown rot diseases seem to be widespread this year. Much of the management for this is preventative, such as practicing sanitary propagation methods. Blueberry season is wrapping up in many areas. High tunnel blackberries are being harvested and field blackberries are close to ripening in northern Ohio. Blackberry yields have been high in central and southern Ohio. Newer blackberry varieties such as Ponca that been planted more and more in recent years have lower acidity and are sweeter, improving sales and customer satisfaction.

For more information or if you have questions, please reach out to a member of the Fruit & Vegetable team or your county extension educator.

Author: Chris Galbraith, Ohio State University Extension/Michigan State University Extension

This article was originally posted on Michigan State University Extension News.

Photo courtesy of MSU Plant and Pest Diagnostics.

Post-harvest rots occurring in vegetable crops can deal a brutal blow both financially and in terms of morale. All the investment and hard work of growing produce is lost if the crop spoils before it can be sold. Fortunately, many of the factors influencing prevalence of post-harvest rots are well-known and there are actions growers can take during the growing season, at-harvest, and post-harvest to reduce losses from premature decay.

What causes a rot?

Once vegetable crops are harvested, they are cut off from their source of nutrients and water. However, the produce continues to respire, using up its energy reserves and releasing water during metabolism. Cellular breakdown occurs as the produce spends its energy/moisture savings without any means of replenishment. As the produce degrades in quality, it becomes more susceptible to colonization by rot-causing pathogens.

There are many different microbes that bring about premature decay if they are able to infect vegetable crops during the different stages of growth and storage. These organisms may be latent pathogens, which can remain quiescent upon entering the crop and begin colonization of host plant tissue during storage (eg. Colletotrichum). Pathogens may also begin colonization immediately after infection, in which case spoilage occurs rapidly. Many rot-causing microbes are considered weak pathogens (eg. different bacterial soft rots), which cannot penetrate healthy plant tissue but instead require wound sites (nicks, scrapes, bruises) to enter and begin colonization. Table 1 lists common post-harvest pathogens for various vegetable crops. Many of these pathogens not only occur in storage but can also cause disease during the growing season.

The disease triangle is a useful framework. Spoilage occurs if the pathogen encounters a susceptible host in conditions that are favorable for infection. Post-harvest spoilage occurs more frequently in warm, wet and humid conditions. High temperatures encourage pathogen activity and increase the rates of produce respiration/ripening. Excess moisture on produce encourages pathogen activity and entry into plant tissue. Similarly, high relative humidity supports free moisture accumulation on vegetable crops in storage. Controlling these factors mitigates risk of premature spoilage and increases the shelf life of vegetable crops.

The disease triangle is a useful framework – spoilage occurs if the pathogen encounters a susceptible host in conditions that are favorable for infection.

Best management practices

Steps can be taken throughout production and storage to minimize losses from post-harvest rots. During the growing season, preventing fruit from coming into contact with the ground using plastic or organic mulch keeps produce cleaner and reduces opportunities for infection. Mulch also helps to reduce soil splash during irrigation or rainfall events, further limiting pathogens from being moved onto susceptible tissue.

Minimizing damage to produce throughout the season reduces wound sites and therefore pathogen entry points. This means gentle handling of vegetable crops at harvest and reducing the number of times produce is touched to minimize accidental skin breaks or bruises. Protecting vegetables from insects, wildlife, and environmental damage (hail, sunscald, wind) also reduces wound sites. Culling produce that is already damaged can reduce spread of spoilage in storage bins. Harvesting at proper maturity also helps optimize shelf-life.

Keeping vegetables cool can go a long way toward preventing premature spoilage. Harvesting during the coolest part of the day and removing the field heat from vegetables immediately after harvest is key. There are different pre-cooling methods available to rapidly bring down the temperature of produce prior to storage, including room-cooling, forced-air cooling, hydrocooling, package icing and vacuum cooling procedures.

Storage temperature and humidity recommendations vary by vegetable crop and following the right guidelines is important for maximizing shelf life. Specific storage recommendations and information on pre-cooling methods can be found in the Guide to Vegetable Production in Ontario (OMAFRA Publication 839). Maintaining proper temperature is also important to prevent chilling or freezing injury, which presents as sunken, water-soaked spots on susceptible produce.

For certain storage crops, curing is a crucial step for optimizing shelf life. Curing allows skins to dry out and harden, increasing protection against infections that cause rot. The area used for curing should always be a well-ventilated space with adequate air circulation. Recommended curing guidelines for several storage vegetable crops are listed in Table 2.

In conclusion, there are various factors that contribute to the occurrence of post-harvest rots. By taking the right action during the growing season, at-harvest, and post-harvest, losses from premature decay can be minimized and crop quality preserved.

This edition of the OSU Extension Fruit & Vegetable Report was written using field observations and expertise from the following OSU Extension staff: Frank Becker, Thomas Becker, Ed Brown, Chris Galbraith, Gary Gao, Kate Hornyak, Carri Jagger, Jim Jasinski, Matt Kleinhenz, Ashley Leach, Dan Lima, Diane Miller, Logan Minter, Francesca Rotondo, Ryan Slaughter

Vegetables

Spider mite flares ups have started to cause damage in watermelon fields. The observed infestations are severe and resulting in rapidly declining plants. Spider mite flare ups are not uncommon during hot and dry conditions, which are currently being experienced by some areas of the state. Frequent or heavy rains typically wash spider mites off of the plants. There are also several natural enemies that can help hold spider mite populations in check such as lacewing larvae, predatory mites, predatory thrips, and minute pirate bugs. Spider mites are typically found in the underside of the leaves. The visual symptoms of their feeding are often observed on the top side of the leaves as the mite feeding damages the cells in the leaves and results in yellowing, stippling and eventually necrotic areas and foliar dieback. When utilizing insecticides for insect control, there is a potential to wipe out beneficial insect populations, allowing for mite flare ups to occur. Also, if you do need to make an application to control mites, make sure you are using a miticide that is labeled for use against the mite species that you are finding and that it has activity on all life stages of the mites. It is common to have all stages of the mites life cycle present at one time, especially as populations increase and generations advance rapidly.  

Spider mite webbing and damage on melon leaves. Photo by Frank Becker, OSU Extension. 

Severe groundhog damage is being reported in various vegetable crops, including those grown at OSU research facilities. Fencing can be used, but the fence must be semi-buried to prevent the varmints from just burrowing underneath it. Trapping is the other most common option. For more information, check out the two articles below: 

Animal Damage Management: Groundhogs – Purdue Extension

Ecology and Management of the Groundhog – Rutgers

There has been a resurgence of flea beetles as the second generation descends on the newer planting of cole crops. Squash bugs, squash vine borer, powdery mildew, and downy mildew are all damaging cucurbits. A flare up of cucumber beetles and bacterial wilt is also occurring. Corn smut is affecting some sweet corn plantings. Oftentimes, desirable and productive varieties may have poor disease resistance to pathogens like corn smut. Cultural practices for reducing incidence of corn smut in your field includes minimizing mechanical damage to plants that provides entry points for pathogens, as well as other standard practices like crop rotation, timely destruction of crop residues, and keeping nutrient levels balanced.

Bacterial diseases are also being reported in peppers. Anthracnose was diagnosed on cucumbers. Fusarium and verticillium are occurring in tomatoes, and Fusarium is also being reported in melons. Bacterial spot is popping up on tomatoes due to the recent heavy rains. 

Early anthracnose infection on cucumber leaves. Photo source: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org

Fruit

It has been a good year for peaches and plums in Ohio. It has also been an early season – Dr. Diane Miller remarked that the variety sequence will be slotted earlier than normal this year. Fire blight risk has decreased considerably. White apple leafhopper has been observed causing moderate feeding damage in several orchards. White apple leafhoppers have piercing-sucking mouthparts that cause yellow-whitish stippling on the leaves. Both adults and nymphs can be found currently when scouting apple trees.  At this point in the season, try to target insecticide applications when you get 3 leafhopper nymphs per 25 leaves/tree. Neonicotinoids are effective against this pest (e.g., Belay (Clothianidin), Actara (Thiamethoxam), Assail (acetamiprid)). Be mindful of the pre-harvest interval since applications of these products at higher rates will increase the interval.  

White apple leafhoppers. Photo by Frank Becker, OSU Extension. 

High mite pressure has been reported in high tunnel raspberries. Are beneficial mites sufficient for mite control in high tunnels or greenhouse settings? It depends on environmental conditions – overly high temperatures can be detrimental for predatory mite survival which causes diminished levels of control. Phytophthora root rot has been reported in raspberries.

Photo by Thomas Becker, OSU Extension. 

With blueberry season in full swing and blackberry season about to get underway in much of the state, Spotted Wing Drosophila is a pest that small fruit growers need to have on their radar. Drosophila suzuki or spotted wing drosophila (SWD) is a fruit fly pest of small, soft-bodied fruits. To be able to identify the adults, many extension educators and specialists have to use a stereo microscope. It would take a hand lens at the very least, and even that may not be enough, as the key identifying features are quite small. Interestingly enough, only the male SWD has the characteristic spotted wing. The wings of the males are mostly clear, with one lone spot near the tip of each wing. Another ID tip for the males that is a bit more difficult to see is the presence of 2 black bands on their front legs. These bands are actually patches of hairs called sex combs. The main identifying feature on the females is their unique ovipositor. The ovipositor is the structure that female insects use to lay/deposit their eggs. For SWD, their ovipositor is lined with two rows of dark colored serrations or teeth. These serrations allow the female SWD to cut into ripening or just ripe fruits. This is different from many of the other fruit fly species we are used to, that infest over ripe or rotten fruit. 

Photo by Thomas Becker, OSU Extension. 

The fruits of primary concern are raspberries, blackberries, grapes, cherries, and strawberries. In Ohio, it seems that strawberries are pretty well done by the time that we start to detect SWD. Generally, first detection occurs when blueberries and raspberries are coming into season. Extension Educators and specialists around the state have SWD traps out to monitor pest populations. First detection is a critical aspect of managing this economically significant pest. The tolerance for damaged or wormy fruit is extremely low. The threshold for management to be implemented is one adult SWD in the trap. According to trapping data collected this year, first detection in the state occurred mid to late June. 

Once SWD is present in the environment, there are a couple of ways to try and manage it. You can start with cultural management by harvesting as thoroughly as you can and disposing of cull fruits. While it might be time consuming and require some extra labor, managing those culls could be worth the time and effort if it means you are removing a host site for the SWD. In addition, the more quickly you can get the fresh fruit off the plants, the less chance the flies have to lay their eggs in them. There are also some recommendations out there for physical exclusion. Berries under plastic, like a high tunnel for example, or under a fine mesh can reduce the number of adults gaining access to the fruit. However, there are some micro-climate considerations to keep in mind. Of note are air movement and access for pollinators (if needed). A fact sheet from Penn State University discusses the potential for biological control. There is apparently work being done to introduce a parasitoid wasp that targets SWD, but this work is still in its early stages. There are also multiple chemical options as well. You can find up-to-date chemical recommendations by checking in the Midwest Fruit Pest Management Guide or contacting your county Extension Educator. Penn State also has a 4-part fact sheet series on SWD with lots of good information. 

Resources: https://extension.umn.edu/yard-and-garden-insects/spotted-wing-drosophila#using-insecticides-2403912 

https://extension.psu.edu/spotted-wing-drosophila-part-1-overview-and-identification 

Orange Rust is a frequent problem on blackberries in Ohio. It is no exception this year. Dr. Gary Gao got a grant from Ohio Vegetable & Small Fruit Research & Development Program this year to evaluate the orange rust disease resistance of two new blackberry varieties from University of Arkansas. The varieties are Caddo and Ponca. A few plants were planted between the orange rusted blackberry plants. In addition, Ryan Slaughter and Dr. Pengfei Wen, a visiting scholar from Shanxi Agricultural University, helped inoculate the new plants with orange rust infected plant leaves. So far, Caddo and Ponca have not shown any symptoms of orange rust. This is a pretty crude field trial. Gary also asked growers about their experiences with Caddo and Ponca.

Photo by Dr. Gary Gao.

Ouachita, a leading blackberry cultivar for Rotatable Cross Arm training system, is reported to have shown good tolerance for orange rust. Growers look for orange rust resistant varieties to extend the harvest season. Caddo started its initial harvest a few says before Ouachita and a few days after Natchez. Caddo’s peak harvest season is also earlier than Ouachita. However, Caddo yield is quite lower than that of Ouachita based on observations in Ohio. 

Sweet-Ark™ Ponca is an early ripening blackberry cultivar with extremely sweet flavor. It ripens at about same time as Natchez. Some of the growers in Ohio have planted Sweet-Ark™ Ponca Blackberries. It is hard to know if this variety will be a good fit for your blackberry operation. However, a blackberry variety with super sweetness may be worth consideration on a small scale. Sweet-Ark™ Ponca blackberry may now be as productive as Ouachita, but early fruit, sub acid and super sweetness may warrant a small planting. Sweet-Ark™ Ponca blackberry is reported to be resistant to orange rust. Hopefully, we will get a better idea about its orange rust resistance after we wrap up our trial.

In addition to planting orange rust resistant blackberry cultivars, a fungicide spray needs to be implemented. Here is an informative article from University of Maryland:  https://extension.umd.edu/resource/orange-rust-bigger-problem-usual-year-brambles/.   Growers can also follow the following link for detailed a spray schedule for blackberries: https://ag.purdue.edu/department/hla/extension/_docs/id-465.pdf 

 This edition of the OSU Extension Fruit & Vegetable Report was written using field observations and expertise from the following OSU Extension staff: Mark Badertscher, Thomas Becker, Chris Galbraith, Melanie Ivey, Carri Jagger, Matt Kleinhenz, Ashley Leach, Gigi Neal, Francesca Rotondo, Sabrina Schirtzinger, Ryan Slaughter

Vegetables

With periods of hot, intense weather so far this season, there have been reports of heat stress in transplants and in hoophouse crops. It is during times like these that managing temperatures in high tunnels becomes of great importance. It can pay to be proactive and utilize strategies for cooling your hoophouse before symptoms appear in your crop. Consider the specific crop, its growth stage, whether it is fruiting vs. non-fruiting, its temperature tolerances, and other factors when determining whether to apply shade cloth, vent the tunnel, or take other measures. Dr. Matt Kleinhenz of the OSU Vegetable Production Systems lab recently gave a lecture on the topic of high tunnel temperature management – check it out at the following link:https://www.youtube.com/watch?v=9dZyPo7Itv4

Squash bugs and squash vine borer are out and feeding. Squash bugs do not seem to be much of an issue yet in some areas. Striped cucumber beetle populations are high and reaching threshold in watermelons and other crops. Some organic growers have been using kaolin clay to prevent cucumber beetle feeding. Kaolin clay can also be applied to black plastic mulch during hot spells in order to cool down the microclimate and reduce heat stress in transplants. Cucumber downy mildew has been found in Ohio. Flea beetle defoliation is being seen in cole crops.  Diamondback moth larvae,  imported cabbageworm, and other caterpillars are out and feeding. Heat blistering on tomato stem tissue was reported during the recent period of extreme heat. There is very high thrips pressure in some pepper plantings. Japanese beetle, slug, and vertebrate wildlife damage is also being reported in various vegetable crops.

Flea beetles can be voracious pests of cole crops, leaving shot hole patterns in leaves. Photo by Chris Galbraith, OSU Extension. 

Fruit

Many abiotic disorders related to the unusual weather have been coming into the diagnostic lab this season. Wooly apple aphids have begun moving out on tender new growth. Diazinon, one of the chief crop protection products for this pest, is no longer being manufactured so control is more of a struggle. Oriental fruit moth populations are peaking. Bacterial leaf spot is being reported in peach. Powdery mildew is also being observed in apples, grapes, and peach.

Bacterial leaf spot can be a severe disease of stone fruits. Photo by U. Mazzucchi, Università di Bologna, Bugwood.org.

Blueberries have been hitting their peak in harvest, around two weeks ahead of normal this year. The strawberry season was reported to be poor this year – berries did not size up well and plants were not as vigorous this season on some farms. 

For more information or if you have questions, please reach out to a member of the Fruit & Vegetable team or your county extension educator.

This edition of the OSU Extension Fruit & Vegetable Report was created using field observations and expertise from the following OSU Extension staff: Mark Badertscher, Frank Becker, Thomas Becker, Ed Brown, Chris Galbraith, Melanie Ivey, Matt Kleinhenz, Ashley Leach, Logan Minter, Gigi Neal, Sabrina Schirtzinger, Ryan Slaughter

Vegetables

A common trend this spring is the delayed planting in many parts of the state due to consistent rainfall that held up field work. Transplants that have been held onto for too long may become rootbound and stressed, exacerbating transplant shock and generally delaying growth and development. With that said, conditions have been dry in other parts of the state such as SE Ohio and could benefit from more rain at this point.

Cucumber beetles are out feeding and bacterial wilt was reported in southern Ohio. Cucumber beetles thresholds are lower for younger plants because of the outsized risk of lethal infection. Seed treatments have been the go-to solution and they seem to be handling pressure well so far this season where they were used. Squash bugs have also emerged and are active. 

Bacterial wilt of cucurbits. Photo by Jim Jasinski, OSU Extension, Bugwood.org

 Flea beetles are feeding in cole crops. Imported cabbageworm and cabbage maggot feeding is severe in some brassica plantings. Heavy imported cabbageworm pressure has been observed in western Ohio.

Severely stunted growth can be an above-ground symptom of cabbage maggot root feeding. Photo by Chris Galbraith, OSU Extension. 

Severe Colorado potato beetle defoliation is being seen in eggplant and potatoes. Some growers have found extended protection using imidacloprid when planting seed pieces. Spinosad is another option in the arsenal, with the added benefit of being organic compliant.

Foliar diseases are being detected in high tunnel tomatoes. Many of these pathogens present on lower foliage first. At the time of fruit set, the lower ⅓ of leaves on tomato plants are generally not particularly productive from a photosynthesis standpoint, and therefore can be pruned to improve airflow between plants. Whitefly and aphid presence has been noted in peppers. Thrip pressure is heavy in onions in some areas.

As is the case every year, spray drift is being observed in vegetables. In some instances, symptoms resembling drift damage may occur on your vegetable crops when there is no obvious source of pesticides nearby. Drift particles may be moved surprisingly far by temperature inversions or other weather conditions. Other times, it may be an issue with herbicide residual activity in the soil.

One question from a community member: Is produce still safe to eat in cases where there is crop damage from pesticide drift? As is the case with most food safety questions – when in doubt, it’s best not to take the risk. There is uncertainty around how long it takes before residue levels are at or below the tolerance levels for situations in which a chemical is not registered for a specific crop. It is better to be on the side of caution when it comes to pesticides and produce safety.

Fruit

Fire blight incidence is high in some apple orchards. Apple scab is also being observed this year, with most infection occurring on fruit rather than foliage. Powdery mildew is being reported. Codling moth flights have been strong this season which is leaving growers with weekly sprays. Dogwood borer flights are particularly strong, and we do not have clear peaks this season. Some rosy and green apple aphids, as well as white apple leafhoppers, are being observed in orchards. 

Bacterial leaf spot is being reported on peaches. Peach leaf curl incidence is also high so far this season. Peach X-disease was recently confirmed by the OSU diagnostic lab. There is oriental fruit moth activity in some peach orchards but seems to be well controlled in most cases.

Foliar symptoms of peach leaf curl. Photo source: Nancy Gregory, University of Delaware, Bugwood.org

There have been calls about thrips and sap beetles in strawberries. 

Similar to vegetables, herbicide drift damage is popping up in vineyards and other fruit. For commercial growers who have experienced significant losses, reach out to ODA to report drift damage. For those wishing to pursue legal action – as soon as damage is observed, store damaged tissue in the freezer for preservation so that it can be tested at a later date.

For more information or if you have questions, please reach out to a member of the Fruit & Vegetable team or your county extension educator.

The OSU Extension Fruit & Vegetable Report is written and published collectively by OSU Extension staff across the state.

Vegetables

Onion plants are off to a quick start this spring. As the plants quickly add leaves, this provides ample opportunity for onion thrips to get started. Scouting for onion thrips is incredibly important early in the season as they become increasingly more difficult to manage as the season progresses and the onion plants become larger and more heavily foliated. Scouting for thrips involves carefully pulling apart onion leaves near the neck and examining down into the crotch of the leaves. On a sunny day, thrips will react to the sudden exposure of sunlight by moving downward, deeper into the leaf collar. As you evaluate management decisions, also be aware that heavy rains may provide assistance in management of onion thrips as the rain washes the thrips out of the leaves or drowns the insect.

Photo by Frank Becker, OSU Extension.

Colorado potato beetles are emerging and becoming active in potato plantings. The adults are very difficult to control with pesticide applications. Control is more effective when applied to newly hatched larvae. Please reference the Midwest Vegetable Production Guide to find effective products for management of the Colorado Potato Beetle. 

Colorado potato beetle larva feeding on potato foliage. Photo by Chris Galbraith, OSU Extension. 

Squash and cucumber continue to be seeded. Striped cucumber beetles are out. As an important reminder, early season control of cucumber beetle is critically important in preventing bacterial wilt in your cucurbit plantings. The threshold for beetles while plants are in the cotyledon stage is 0.5 beetles per plant. The threshold for beetles at the 3-4 leaf stage is 1-2 beetles per plant, and for plants with 4 or more leaves, 3-5 beetles per plant. Scouting during the morning or evening will give you the best results, as beetles are often difficult to find during the heat of the day. Recent chewing and feeding damage can also be indicative of beetle activity. This can be differentiated from “old” feeding damage as the older damage will look scabbed over, but the recent feeding will appear as a “wet” wound.

Cabbage maggot, caterpillar, and swede midge damage is being observed in cole crops. Reports of some early season flea beetle activity have led to some growers already making applications to limit damage to young cole crops. Flea beetle feeding can be scouted for by looking for “shot hole” style feeding patterns on the foliage of the plants. Early season feeding, especially on young transplants can significantly stunt the plants, and in some cases when feeding is severe enough, seedling death can occur. 

High tunnel tomatoes are fruiting and field tomatoes are being planted where growers can get into the fields. 2-4,D drift damage has been observed in some high tunnels. Powdery mildew and thrips are the main pest of concern in greenhouse tomatoes at this point in the season. 

Early blight and powdery mildew have both been found in high tunnel tomatoes. Powdery mildew, as the name describes looks like powdered sugar on the upper leaf surface. These symptoms can develop at any level of the plant.  Early blight, or Alternaria, has an alternating ring/bullseye like pattern, often with a yellow halo around the lesion. Early blight is most often first found on the older foliage near the bottom of the plant.  Please scout your high tunnel tomatoes frequently and thoroughly, especially early season to catch early season disease presence and hopefully prevent major impacts throughout the season. Please read fungicide labels carefully to make sure that the crop and disease are both listed on the label. Remember, the label is the law. 

Recently planted sweet corn is beginning to emerge. Slug damage is being observed, although not severe at this point. Now is also an important time to be checking sweet corn for black cutworm. Cutworms damage the pants by cutting the plant off at or slightly below the soil line, significantly stunting the plant or causing plant death. If infestation levels are high enough, stand loss can occur to the point of necessitating a replant. 

Fruit

With the mild winter, fruit, vegetable, and agronomic crops alike are getting a quick start in Ohio this year! It seems the pathogens got the memo as well as educators and specialists around the state are reporting an early onset of several diseases on fruit. One disease that we are seeing in orchards this spring is apple powdery mildew.

Powdery mildews are among one of the more recognizable diseases in our specialty crops and can have a significant impact. Some folks are probably familiar with the cucurbit powdery mildew that we find on the cucumbers, zucchini, and other cucurbit crops in our fields in gardens. Powdery mildews are host specific, so the powdery that we observe on apple trees will not lead to powdery mildew infections in our cucurbit crops. They are different species. Usually, we see cucurbit powdery mildew as we get further into summer, around July. That particular pathogen does not overwinter in Ohio and has to be blown in by the wind from areas where it can overwinter.

Apple powdery mildew is quite different, caused by the species Podosphaera leucotricha. Apple powdery mildew can overwinter in fruit buds that were infected in the previous season. Another interesting thing about powdery mildew is that while it does need a higher relative humidity, it does not require free water for development. Many of our other diseases do have that requirement. So, even in drier years, powdery mildew can still pose a challenge.

Powdery mildew is one of those diseases where when we scout, we can observe both the signs and symptoms of the disease. In other words, we can see both the physical evidence of the powdery (Sign: the white fungal growth) as well as the plants response to the infection (Symptom: stunted, crinkled leaves). The first thing you will likely see in spring is the white fuzzy or waxy appearance to the leaves. As the disease persists, leaves will become stunted, crinkled, and brittle. As the season goes on, the disease can spread to the twigs, stunting their growth, and potentially leading to dieback issues. In severe cases, symptoms can show up on fruit resulting in russetted apples.

Photos by Thomas Becker, OSU Extension.

Apple powdery mildew can be managed with some cultural integrated pest management tactics. One tactic is to plant varieties that are less susceptible or potentially resistant to powdery mildew. Another tactic is to plant and manage your trees to allow for good air movement and light penetration. This can lower the relative humidity around the trees and make it more difficult for the pathogen to get established. Chemical controls are also an option. If powdery is a persistent problem in your orchard, it may require the development of a good fungicide program to get adequate control. Contact your county extension educator, one of our state specialists, or reference the Midwest Fruit Pest Management Guide for current fungicide recommendations.

References:

•         Ohioline Apple Powdery Mildew Fact Sheet, https://ohioline.osu.edu/factsheet/plpath-fru-21
•         Powdery Mildews, Colorado State University Extension, https://extension.colostate.edu/topic-areas/yard-garden/powdery-mildews-2-902/
•         Apple Powdery Mildew, Washinton State University, https://treefruit.wsu.edu/apple-powdery-mildew/

Apples have progressed quickly in their development. Codling moth trap catches are high across the state. Insecticides to control first generation codling moth should be on to slow the second generation. Wooly Apple Aphids are on the move in the trees, as they move from the roots to the limbs. San Jose Scale is present as well and male flight has been observed in southern Ohio. Plum curculio damage present (petal fall applications are best to control infestations). Pear psylla adults active. 

Lacewing eggs hanging from branch. Lacewings are beneficial insects that feeds on aphids and other fruit & vegetable pests. Photo by Frank Becker, OSU Extension. 

Strawberries are ripening and some varieties are in harvest. Main pests at this point are slugs, spittlebugs and birds. Phytophthora leather rot and sun scald being observed in fruit. Brambles are blooming, blueberries setting fruit. 

For more information or if you have questions, please reach out to a member of the Fruit & Vegetable team or your county extension educator.