Wayne County IPM Notes From the Week of June 14-18

Vegetable Crops

            This growing season, so far, has been all about the bugs. We have not had a huge amount of disease pressure

Squash bug eggs on summer squash.

on the vegetable crops in our area. We have, however, continued to find more insects impacting local crops.

Newly spotted insect pests this week included Japanese Beetles, thrips, and squash bugs. The Japanese Beetles were found in silking sweet corn, the thrips are being found in onions and the squash bugs are being found laying eggs in summer squash plantings.

 

Japanese Beetle found in a sweet corn stand.

In green beans we are still seeing a light population of potato leaf hoppers and a few bean leaf beetles feeding here and there. Cucurbits still have some cucumber beetles feeding, as well as some aphids. Aphids are not picky about which crops they are in, as we continue to find them in a variety of crops, including peppers and tomatoes. Both eggplant and potatoes are dealing with flea beetle and Colorado potato beetle. The Colorado potato beetle larva are becoming very prolific in some areas and causing significant defoliation. Cole crops, while also dealing with pressure from flea beetle, are now seeing an increase in activity from the imported cabbage worm caterpillar.

Small Fruit and Orchards

Aphids and mites are being found in fruit trees, primarily apple trees. This week, we began to find European red mites, green apple aphids and wooly apple aphids. Trap counts for CM in apples and OFM in peaches were all below threshold, with many traps reporting zeros.

The biggest update in our pest outlook in small fruit was not an insect, instead it involved birds. There was bird damage being found in strawberries, as well as in blueberry areas where the berries are starting to color. Some growers are using netting to exclude the birds from blueberry plantings. This is a lot of work but saves a lot of berries from being damaged.

Wayne County IPM Program Scouting Notes From the Week of June 1- June 4

Vegetable Crops

Cucumber beetle feeding on the foliage of a summer squash plant.

Insects continue to be the main headline in the vegetable crops in our area. Of greatest concern is the cucumber beetle. The populations continue to increase in number and the efficacy of seed treatments or in-furrow applied insecticide starts to decline 4-6 weeks after the seed germinates or after the insecticide is applied. This means that more of the beetles are feeding without being affected by the insecticide. Be sure to scout cucurbit crops frequently and carefully to get accurate counts of the beetles. The thresholds for cucumber beetles are as follows: Cotyledon stage – .5 beetles per plant, 2-4 leaf stage – 1 beetle per plant, greater than 4 leaves – 3 beetles per plant. Limiting the amount of feeding that cucumber beetles do will also limit the amount of bacterial wilt occurring in these plantings. Do be cognizant of the plants that are in bloom and limit your spraying to a time when it will be least impactful on the pollinators.

 

Colorado potato beetle larva feeding on a potato plant. Tommy Becker photo.

Other insects that were spotted this week include Colorado Potato Beetle larvae and imported cabbage worms. Both of these pests can cause significant damage in their respective crops when left unchecked. Flea beetles also continue to feed on plantings of cole crops, preferring young transplants versus older, more established plantings, although both should be inspected for beetles.

Sweet corn plantings are growing quickly and some plantings that were done into plastic mulch and covered this spring already have a few tassels poking out. Overall, there has been no major concerns in the sweet corn plantings so far, however, do your best to keep up on weed control. Weeds such as bindweed, thistle, and ragweed can not only compete for resources, but can also make harvest difficult and may serve as refuge locations for insect pests to retreat to.

Small Fruit and Orchards

We are beginning to enter a critical period for managing diseases in grapes. This period, which extends from immediate pre-bloom through four to five weeks post bloom, is a critical time to control fruit infections by the pathogens which cause black rot, powdery mildew, and downy mildew. According to the 2021-2022 Midwest Fruit Pest Management Guide, the fruit of the most commonly planted varieties becomes resistant to infection by these diseases by four to five weeks after bloom.

In strawberry plantings we are seeing a lot of green fruit and in some locations, harvest is beginning to ramp up. Overall, there have been very few concerns in the

Blueberries starting to enter the “fruit coloring” stage.

strawberries to this point, with just a few slugs here and there and a spotting of powdery mildew on a few plants. Powdery mildew is managed by spraying either pre-bloom or during the early bloom through bloom stage.

Other small fruit like blueberries and brambles look to have a heavy fruit set this year. Blueberries are beginning to get some color to them, and the blackberry and raspberries are either in bloom or in fruit development.

In apple and peach orchards, the fruit are noticeably starting to increase in size. We are finding some aphids in apple trees, feeding on the leaves and new shoots. In peaches, we did find a few instances of powdery mildew affecting the fruit. Trap counts for OFM and CM were under threshold in all of our traps this week. The counts are down after last week with several orchards above threshold for CM and OFM counts.

Wayne County IPM Notes from the Week of May 17th – May 21st, 2021

Vegetable Crops

             As we move into warmer temperatures, it would be best to remove row covers from field planted crops in the interest of pollination and reducing heat stress. In crops that do not need pollinated such as cole crops, the row cover can serve as an insect barrier and prevent early infestation from the Imported Cabbageworm. Crops such as summer squash, cucumbers and tomatoes

Flea beetles feeding on a recently transplanted brassica plant.

all need to be uncovered sooner than later to avoid poor pollination and subsequently, poor fruit set.

Hot weather can also be problematic when transplanting into black plastic. The black plastic can become very hot and planting a young, tender transplant into the plastic on a hot, sunny day can cause a significant amount of stress, burns on the leaves and stems and in some cases, death of the transplant. Try to plant in the evenings, as temperatures cool down or on cloudy, cooler days.

Colorado Potato Beetle adults on a potato plant.

In the last week we have seen an explosion of flea beetle in cole crops, and the Colorado potato beetles have begun to make their way into potato plantings. Frequent scouting and monitoring of these insect pests is extremely important. Large populations on young plants can stunt their growth and reduce yields. Conditions have been ideal for rapid population increases, hence the need for frequent scouting. An interesting insect problem we observed was a planting of cole crops where the roots of some plants were being destroyed by ants. In most cases, as you turn on your irrigation lines under plastic, it will drive the ants elsewhere.

Generally speaking, disease pressure has been very low in vegetable crops to this point. We have observed some early blight in a tomato high tunnel, as well as blossom end rot in high tunnel tomatoes.

Small Fruit and Orchards

            Apples and peaches are both reaching fruit development. There was significant growth and change in the size of the fruit over the past week. Out of all of

Strawberry blooms with black centers, damaged by freezing temperatures, alongside healthy blooms.

the orchard traps that we have out, we caught 1 OFM and 1 CM. We began to find aphids in apple orchards. The feeding was evident by curling leaves and shoots.

Blueberries are in petal fall and are setting fruit. Raspberries are getting ready to bloom and overall seem to be coming along just fine.

Grape bud that had been damaged due to freezing temperatures now showing secondary growth. Tommy Becker photo.

Strawberry varieties that were early to bloom, and left uncovered, likely suffered heavy bloom loss due to the freezing temperatures that we experienced. Some early blooming varieties had very few, if any, healthy looking blooms. Many plants have put on new blooms, which are very easy to distinguish from the frosted blooms. Early varieties of plasticulutre strawberries that were covered and protected from the cold are setting fruit and beginning to ripen and may even be in harvest. We are not finding any thrips at this time. Unfortunately, we are finding a lot of slugs in strawberry plants and on the berries.

Currently, grapes are now past the bud burst stage, as most are at the 4-8” shoot stage.  We are beginning to see where grape buds that had been damaged due to freezing temperatures are putting out secondary buds and shoot growth, which is very promising

Be on lookout for thrips on strawberries

Thrips can be a serious pest of strawberries, but they are an occasional pest. This means that in most years, they are not a problem, but in some years, they can be a big problem. The reason for variability from year to year seems to be related to weather systems. In some years, conditions are right that large numbers of small insects such as thrips and leafhoppers blow into Ohio on weather fronts from the southern USA during the time that strawberries are in bloom. In other years, this long-distance movement does not happen at all, or happens later, at a time when strawberries are no longer in bloom. Due to the irregularity in the occurrence of thrips, it is a pest that is well suited to weekly scouting, for early detection of any infestation.

Strawberry fruit that have been injured by thrips are a dull or bronzed color, and are often small, hard, seedy, and fail to ripen (Figure 1). Thrips can cause uneven maturity of fruit. When thrips are abundant and the berry injury is severe, the result can be a strawberry crop that is completely unmarketable. Diagnosis of thrips injury can be tricky because thrips are not the only cause of fruit bronzing. Bronzing can be due to feeding by cyclamen mite or two-spotted spider mite, or to infection by powdery mildew, or to occurrence of low temperatures or hot dry winds, or to pesticide spray effects.

Thrips are often overlooked due to their small size and their tendency to hide in protected places. Thrips are weak fliers but fast runners. Thrips are small, slender, elongate, ‘cigar-shaped’ insects (Figure 2), about 1 mm (1/25 inch) long as adults. They differ from other insects by having narrow strap-like wings that are fringed with hairs. The wings are usually folded lengthwise over their back when they are resting or feeding. The immature thrips are the same shape as adults but smaller and without wings. Thrips have lopsided mouthparts that have a well-developed left mandible and an underdeveloped right mandible. They feed by piercing and scraping plant cells with the mandible then sucking sap that oozes out of the punctured cells.

The thrips species that most commonly infests outdoor strawberries is Frankliniella tritici, which has the official common name of ‘flower thrips’, but which is widely known as the ‘eastern flower thrips’. The adults are yellowish brown, and the immatures are whitish-yellow. The eastern flower thrips does not tolerate cold weather, so does not survive winter well in places like Ohio. The eastern flower thrips has a wide host range that includes many flowering weeds, where the thrips population can build up before moving into a cultivated crop like strawberries.

The eastern flower thrips looks quite similar to three other species of thrips that inhabit Ohio and have been reported from strawberries: the western flower thrips (Frankliniella occidentalis), the tobacco thrips (Frankliniella fusca), and the onion thrips (Thrips tabaci). The western flower thrips is the species commonly found in greenhouses; it is generally much more difficult to control than other thrips because it is usually resistant to most insecticides. In greenhouses, the western flower thrips causes injury to tomatoes, peppers, and cucumbers as well as to strawberries. The onion thrips is best known as a serious pest of dry bulb onions, green onions, and cabbage but is sometimes found on other crops.

Thrips generally prefer to feed on flowers rather than other plant parts, but they can feed on leaves and fruits. On strawberries, the infestation starts by adult thrips being attracted to flowers, and the female inserts eggs at the base of flowers. Each female can lay about 80 eggs. Infestation can continue during fruit set by adults and their immature offspring. Thrips feed on pollen, seeds, and the fruit tissue between seeds. Thrips hide under the cap of the berry or in grooves around the seeds on the berry.

A key to thrips management is frequent monitoring by scouting, at least once per week. Growers should designate one person on the farm to be sure that scouting is done every week. Where multiple varieties are present, each variety should be scouted separately. The scout should begin the season by examining early flower clusters on early cultivars, as soon as the first blossoms open. Scouting should be done in five different areas within small fields or in ten different areas within large fields. In each area, 10 blossoms should be tapped into a white cup, or into a zip-top sandwich bag, which should then be examined for the dislodged thrips running around on the surface. Count the number of thrips found, then calculate the average number of thrips per blossom. The action threshold for treatment with insecticide, used the midwestern USA, is the presence of 2 or more thrips per blossom. This is a conservative threshold that is lower than a threshold of 10 thrips per blossom that is used in some mid-Atlantic and California regions.

Scouting should continue after fruit set, until fruit are ½ inch diameter, by examining 50 fruit in each area, and counting thrips on those fruit. Fruit can be examined in place, or removed and put in a plastic zip-top bag, which can be placed in a sunny location so that the heat forces the thrips to leave their hiding spots and begin running around on the bag surface. Once fruit are ¼ inch in diameter, an action threshold is 0.5 thrips per fruit.

If thrips are above threshold, the trickiest part of management is to avoid spraying insecticide that will harm pollinators. Insecticide should not be applied during bloom, to protect bees and other pollinators. Insecticide should be applied pre-bloom or before 10% of the plants have open blossoms. If thrips are found above threshold on early cultivars, then a preventive spray can be made on the later cultivars before their flowers open, to avoid harming pollinators. If insecticide is needed during bloom, it should be applied in the evening when bees are least active. Sprays targeted at tarnished plant bug or spittlebug or strawberry clipper weevil, just before bloom, often do a good job of controlling any thrips that also are present.

Insecticides used to manage thrips on conventional strawberries include several products that are labelled for control, and several that are labelled only for suppression (Table 1). Products for control of adult and immature thrips are Radiant, Assail, Apta, and Dibrom, all of which have thrips listed as a target pest on their labels. Note that use of Apta on strawberries appears on a supplemental label, not the federal label. A product for control of immature thrips, but not adults, is Rimon. Products for suppression of thrips are Closer, Exirel, Sivanto, Transform, and Verdepryn. In addition, there are several products that are allowed for use on strawberries, but that do not list thrips as a target pest on strawberry, however thrips are a target pest of these products on other crops; these are Admire Pro, Agri-Mek, Brigade, Danitol, Harvanta, Lorsban, and Malathion. Note that Lorsban has a 21-day pre-harvest interval thus is for use only pre-bloom. Beware that pyrethroid insecticides such as Brigade and Danitol are no longer as effective as they were in the past due to the development of resistance in thrips populations at many locations. An adjuvant that can be helpful in control of thrips is Wetcit, which is a penetrant, spreader, and wetting aid.

Products for thrips control on organic strawberries are Entrust, azadirachtin products such as Neemix and Aza-Direct, and the beneficial fungus Beauveria bassiana, as well as other natural products (Table 2).

An important natural enemy of thrips is the Orius predatory flower bug, which is a very small true bug that preys on thrips adults and thrips larvae. Orius insidiosus is a common species in Ohio on many crops; it is frequently found on the moist fresh silks of sweet corn and on flowers of Queen Anne’s lace. There are also several species of predatory mites that prey on thrips. The local population of these natural enemies is often inadequate to suppress thrips, but growers who would like to take a biological control approach to thrips management can purchase natural enemies from commercial insectaries: Orius (predatory flower bugs), and four species of predatory mites: Ambylseius swirskii, Neoseiulus (Amblyseius) cucumeris, Amblydromalus limonicus, and Stratiolaelaps scimitus (formerly Hypoaspis miles). Beneficial nematodes such as Steinernema feltiae are another option. Some suppliers of these natural enemies are IPM Labs, Koppert, BioBest, and Rincon-Vitova. Biocontrol is not feasible to begin once the thrips population is large, but can be planned in advance at locations that have a consistent problem with thrips.

-Celeste Welty, Extension Entomologist

 

Wayne County IPM Notes from September 20-26

Vegetable Pests

Aphids feeding on pumpkin leaves. F. Becker photo.

Cucurbit growers need to check their crops for infestations of aphids. Large populations of aphids can be found feeding on the underside of leaves. While the feeding on the foliage is not of major concern at this point in the growing season, the exudate from the aphids is. Aphids secrete a sticky substance known as honeydew and when large amounts of the honeydew are being formed, it can drip down onto the pumpkins and result in black sooty mold growing on the fruit.

Continue to keep watch over late season cole crops as there are still a lot of imported cabbageworm adult butterflies in and around crops such as broccoli, cabbage, brussels sprouts, and cauliflower. Additionally, other fall insect pests such as the cabbage looper and aphids can become problematic. Aphids can have rampant infestations during cooler and dry weather.  Therefore, routine scouting, especially at this time of year, is important to effective pest detection and management.

Imported cabbageworm larva feeding on cole crop leaves. F. Becker photo.

Fruit and Vegetable Diseases

Residue management of fruit and vegetable crops is an important component of integrated disease management. Typically, at the end of the season, plants are commonly being affected by a range of diseases. As management of these diseases dwindles towards the end of the season, there is an increased level of inoculum that may be able to over winter. Many of the pathogens affecting the plants now are able to over winter and result in disease challenges again next year. It is important to know what diseases you have in your fields. This knowledge can help you make crop management decisions such as how long to rotate out of a certain crop. Additionally, the residue that is left at the end of the season should either be composted or tilled into the soil as soon as possible. Composting or incorporating the crop residue allows for the plant to be broken down by soil microorganisms and prevents the spread of the pathogen to other plants that may be alternative hosts that could overwinter the pathogen. Doing this in association with crop rotation will help give time for the pathogens to die off. Typical crop rotations allow for 3-

A field that has been cleared of plant debris, run through with a disc and then planted with cover crops. F. Becker photo.

4 years between planting a crop in the same family.

Fruit Pests

Stink bugs are still active and can be found along wood-lines and field edges. Although, numbers do seem to be dropping as the summer comes to an end. I am still finding the occasional fruit that has been damaged by a stink bug. The damage is typically occurring in trees along the edges of orchard blocks, especially near wooded areas.

Wayne County IPM Notes from September 13-September 19

Vegetable Pests

Large masses of cucumber beetles on pumpkin plants late in the season. F. Becker photo.

Cucumber beetles continue to have high populations in pumpkin fields. The spotted cucumber beetle, which is also the southern corn rootworm adult, are migrating in masses out of corn fields as corn silks dry down and finding their way into pumpkin fields. So long as the beetles are not chewing on the skin of the pumpkin, they are not anything to be concerned about, however, if they start damaging the skin of the fall vine crops, an insecticide application may be warranted.

Scouting your latest plantings of cole crops is recommended to make sure that cabbageworms do not get out of hand. It can be easy to let your guard down as the season winds down, but if you want to have a marketable crop, you need to keep an eye out for the imported cabbageworms doing damage.

Vegetable Diseases

Peppers, at this point in the season should be winding down, however, disease pressure can force a premature end

Anthracnose lesions on a bell pepper. F. Becker photo.

to the season quite rapidly. One disease that can cause a rapid decline in peppers is anthracnose. At this point in the season, it is not worth the investment in any fungicide applications. For future planning, practice a three-year crop rotation with crops that are not in the Solanaceae family and consider doing seed disinfestation before planting. This disease can be managed with fungicides; however, it is important to address the issue of the origin of the diseases, rather than trying to fix the issue by applying a rescue fungicide every year.

At this point in the season, it is of your best interest to consider the cost of any fungicide application in respect to how much more you expect to get out of a crop. With pumpkins, for example, as the plants are beginning to die off at this point in the season, it is not likely that any fungicide application will be effective or result in any increase of yield or crop value. For a crop like cole crops that are just a few weeks in the ground, then you may have opportunity to apply fungicides, should the need arise. As always, follow the label and pay close attention to the pre-harvest interval when applying a fungicide.

Fruit Pests

Stink bugs are still active and can be found along wood-lines and field edges. I am still finding the occasional fruit that has been damaged by a stink bug. The damage is typically occurring in trees along the edges of orchard blocks, especially near wooded areas.

Fruit Diseases

Apples are now ripening and being harvested in orchards around Wayne County. F. Becker photo.

As fruit continues to ripen and be harvested, we continue to move forward through the growing season without many disease issues in our area. If you are doing any final treatments for fruit diseases, pay close attention to the PHI on the product label. The pre-harvest interval determines how long after you applied that product that you may harvest the crop. This is especially important to pay attention to as many varieties of orchard crops as well as grapes are maturing and nearing harvest.

Late Season Pumpkin Pest – Aphids

Jim Jasinski, Department of Extension; Celeste Welty, Department of Entomology

Aphids on lower leaf surface.

While most growers have focused on managing cucumber beetles and squash bugs to this point in the season, now it’s time to be vigilant for a common late season pest, aphids. While there can be several species of aphids that invade pumpkin and squash fields in mid to late summer, the melon aphid is likely most common. Regardless of the species in your field, aphid biology and management are similar.

More aphids on a leaf.

Like squash bugs, aphids have sucking mouth parts. Aphids feed on the underside of leaves where tremendously large populations can build up quickly even with natural enemies (ladybugs, green lacewing larvae, parasitoid wasps, syrphid fly larvae, etc.) in the field, especially under hot and dry conditions. A by-product of their feeding is called honeydew, and when high aphid

populations exist, this sticky liquid can drip onto foliage and fruit creating a perfect condition for black sooty mold to grow on the surface of fruit which will need to be washed off prior to sale.

While aphids can create the environment for sooty mold, they can actively vector viruses to pumpkin and squash plants. A survey conducted in the late 1990’s by OSU researchers concluded that Watermelon Mosaic Virus was the most common type of virus found in Ohio pumpkin fields. Viruses in general may not be a serious threat to older plants where the fruit mature, but for younger plants with immature and developing fruit, distorted and strappy leaves, bumpy mosaic colored fruit or no fruit may result. While it is possible to treat pumpkin and squash plants for aphids, if an aphid feeds on a plant for just a second and then picks up a lethal dose of insecticide, the virus may already be vectored to that plant.  As a practical matter, virus transmission cannot be stopped using insecticides alone. Timing of planting is perhaps more effective, with earlier planting leading to potentially less virus incidence because fewer aphids are present as the crop matures.

Pumpkin leaves infected with virus.

Fruit infected with virus.

Sooty mold on pumpkin rind.

Sooty mold on foliage.

If scouting reveals aphid populations building in a field, even in the presence of natural enemies, treatment may be warranted if honeydew and black sooty mold are seen. While pyrethroids are relatively inexpensive to apply, they are devastating against most natural enemies and will likely cause an even more severe outbreak of aphids soon after application. The following products are non-pyrethroid alternatives, and their relative price compared to pyrethroids ($) are listed. Recent systemic materials such as Beleaf ($$$) and Fulfill ($$$) target sucking pests and should be less disruptive to natural enemies.  Other products such as Assail ($$), Sivanto ($$$), Harvanta ($$$$), and Exirel ($$$$$) are also likely to have high efficacy and less disruptive to non-target pests. A full list of recommended insecticides and their PHI’s can be found in the Midwest Vegetable Growers Guide (https://mwveguide.org).  

Wayne County IPM Notes from August 30 – September 5

Vegetable Pests

Various sizes of stink bug nymphs in the leaf litter of fall vine crops. F. Becker photo.

With daytime high temperatures becoming cooler, we are starting to see more and more activity from the squash bugs. If you are actively harvesting your fall vine crops, the squash bugs may not be of concern to you. However, if you are not yet harvesting or choosing to leave your fall vine crops out in the field, the squash bugs can and will do damage to the skin of the pumpkins and gourds. The best time to scout your fields to look for squash bugs is early in the morning or into the evening when they are not in direct sunlight. More on squash bug management.

Cucumber beetles have made a late season come back, much to the dismay of many fall vine crop growers. The cucumber beetles, this late in the season, tend to do very little damage to the foliage of the plants. What they do go for is the fruit instead. Beetles will damage the skins of pumpkins and gourds. This leaves the pumpkins and gourds as less desirable crops and also opens them up to infection and secondary insect pests that would otherwise not affect the fruit.

Late season damage being done by cucumber beetles. F. Becker photo.

Stink bugs are out and doing damage to crops such as tomatoes. The stink bugs activity and feeding starts to increase most noticeably from late July through August and they remain active through the end of the growing season. Their damage on green tomatoes may appear as small, whiteish areas. On ripe tomatoes, the damage shows up as a golden yellow “starburst” pattern. While this damage is typically only cosmetic, higher amounts of feeding can result in infection and result in the fruit being unmarketable.

Vegetable Diseases

Plectosporium blight on pumpkin can cause significant crop losses. The disease typically presents itself as diamond shaped lesions on the stems and can also affect the veins on the leaves, although it can infect all parts of the plant. The lesions start out small but can quickly cover the entire stem. This disease has started to show up within the last few weeks in Ohio due to the favorable conditions of rain, and cooler temperatures.

Plectosporium blight lesions on a pumpkin stem. F. Becker photo.

A common thing to see in pumpkin fields as plants are maturing is yellowing leaves and the leaves starting to die back. Although there may be diseases such as powdery mildew present in the field, this rapid deterioration is not likely solely the result of the disease pressure and rather the natural senescence of the plant. As the plant matures and the pumpkins and gourds begin to cure, the plant has essentially reached the end of its life cycle. The leaves begin to change from dark green to a pale green/yellowish color and will eventually begin to die back. So long as this is happening at the end of the season and the pumpkins and gourds are mature, there should be no concern.

Fruit Pests

Spotted wing drosophila have been active in small fruits for some time, but with peaches now being harvested, the SWD can and will target the peaches as well. I have found peaches that have SWD larva feeding just under the skin. SWD can also do damage to grapes. I have started to find berries in grape clusters that were soft or looked poorly. Just under the skin of these grapes I found SWD larva feeding and moving around. Many grapes are ripening and getting close to harvest so anyone with grapes should consider treating for SWD.

Stink bugs can also do a lot of damage to fruit crops this time of year. I have set out traps and they are already showing very active stink bug populations. I am also finding damage from stink bugs in orchard crops. Most of the damage I am finding has been occurring in apples. This damage appears as a discolored depression in the skin with corking of the flesh all the way up to the skin. This damage can occur anywhere on the apple, although it can be frequently found on the “shoulder” of the fruit.

Fruit Diseases

Overall, disease pressure has been fairly limited this year. Hot and dry conditions have prevented favorable conditions needed for disease development. As fruit continues to ripen and be harvested, we continue to move forward through the growing season without many disease issues in our area. If you are doing any final treatments for fruit diseases, pay close attention to the PHI on the product label. The pre-harvest interval determines how long after you applied that product that you may harvest the crop. This is especially important to pay attention to as many varieties of orchard crops as well as grapes are maturing and nearing harvest.

Apple that has cracked and split after a heavy rain following drought conditions. F. Becker photo.

After this recent round of heavy rain and subsequent heat and high humidity, apple growers should be aware that some apples may crack or split while still on the tree. We are fortunate that we were beginning to have some more frequent rains that were starting to alleviate drought conditions, and this prevented rapid uptake from the trees. Typically, when a heavy rain occurs after prolonged dry spells or during drought conditions, there is large amounts of moisture taken up through the roots as well as absorbed through the skin of the fruit. This results in rapid cell expansion and thus cracking, and splitting occurs.

Do you recognize stink bug injury on sweet corn?

As the brown marmorated stink bug (BMSB) becomes more well established around Ohio, its injury on sweet corn is becoming noticeable. In plantings that are sprayed frequently with pyrethroids such as Warrior or Hero for control of corn earworm, injury by stink bug is less likely to occur because pyrethroids are among the few insecticides that are toxic to stink bugs. But in plantings of transgenic sweet corn that do not need to be sprayed with insecticide for worm control, or in sweet corn that is sprayed by Coragen or Radiant for worm control, injury by stink bug is more likely to occur. Stink bugs feed by sucking juices from the kernels, after inserting their mouthparts through the husks (Figure 1). This results in kernels that are shrunken in a variety of ways, as shown in Figures 2 and 3 below. Both the adults (Figure 4) and the immature nymphs (Figure 5) feed on the kernels. The injury can occur anywhere on the ear; sometimes it is clustered near the tip, other times it is scattered along the entire length of the ear. In addition to sweet corn, BMSB has a wide range of host plants, ranging from raspberries, peaches, apples, and grapes to bell peppers, eggplant, green beans, swiss chard, and tomatoes.

-Celeste Welty, Extension Entomologist

Figure 1. Sweet corn ear being fed upon by adults and nymphs of the brown marmorated stink bug.

 

Figure 2. Sweet corn ear with many kernels injured by stink bug feeding.

 

Figure 3. Close-up view of kernels damaged by stink bug.

 

Figure 4. Adult of the brown marmorated stink bug.

 

Figure 5. Nymph of the brown marmorated stink bug.

Wayne County IPM Notes from August 16 – August 22

Vegetable Pests

Stink bugs have started to feed on and damage crops such as tomatoes. The stink bugs activity and feeding starts to increase most noticeably from late July through August and they remain active through the end of the growing season. Their damage on green tomatoes may appear as small, whitish areas. On ripe tomatoes, the damage shows up as a golden yellow “starburst” pattern. While this damage is typically only cosmetic, higher amounts of feeding can result in infection and result in the fruit being unmarketable.

Flea beetles feeding on young, fall planted, cole crops. F. Becker photo

Flea beetles continue to feed on several crops including tomatoes and cole crops. The feeding on tomato plants is not of major concern mostly because the damage I am seeing is on the lower leaves. The damage on cole crops is of more concern due to the areas of the plants being damaged. The flea beetles are feeding on young tender leaves on kale plants as well as causing heavy damage on young plantings of broccoli and cabbage. Too much damage at this point can stunt the plants growth and result in reduced yield.

The trap counts for sweet corn pests in Wayne County are overall down. Sweet corn growers should be keeping an eye out for army worm damage as we have had reports of high fall army worm trap counts as well as damage that was being done by the yellow striped army worm. More on recent trap counts

Vegetable Diseases

            Downy Mildew is in Wayne and Medina counties and likely in surrounding counties as well. Cucumber growers need to be spraying for downy mildew.

Powdery mildew can be just as destructive on squash as downy mildew is on cucumbers. I have been finding powdery mildew consistently in younger squash plantings. Unfortunately, the earlier the plant is infected with powdery mildew, the shorter the life span of the plant. With an infected plant having a short life span, the yield for the plant can also be expected to decrease.

Smut is especially prevalent on sweet corn this year. Smut is more common during hot and dry weather, especially when followed by a heavy, warm rain. This year has been the perfect year for prime smut infection and growth.

In some pepper fields, there has been a few spots of anthracnose found on the fruit. Anthracnose typically does not affect the pepper foliage; however, the pepper fruits are highly susceptible to infection from the disease. Peppers develop large sunken lesions with pink to orange colored spores. This disease can be found typically on the lower sets of fruit, where they are more likely to be splashed with soil from heavy rains.

Fruit Pests

Spotted wing drosophila have been active in small fruits for some time, but with peaches starting to ripen, the SWD can and will target the peaches as well. I have started to find peaches that have SWD larva feeding just under the skin.

SWD can also do damage to grapes. This week I started to find berries in grape clusters that were soft or looked poorly. Just under the skin of these grapes I found SWD larva feeding and moving around. Many grapes are ripening and getting close to harvest so anyone with grapes should consider treating for SWD.

Brown marmorated stink bug trap with adults and nymphs present. F. Becker photo.

Stink bugs can also do a lot of damage to fruit crops this time of year. We have traps out for the brown marmorated stink bug, which will help us monitor its population, however, I am already finding some stink bug damage on peaches and apples. This damage appears as a discolored depression in the skin with corking of the flesh all the way up to the skin. This damage can occur anywhere on the apple.

Fruit Diseases

            Overall, disease pressure has been fairly limited this year. Hot and dry conditions have prevented favorable conditions needed for disease development. As fruit continues to ripen and be harvested, we continue to move forward through the growing season without many disease issues in our area.

Some grape varieties are nearing harvest. At this point, there should be no significant disease concerns, especially so close to harvest. The same goes for orchard crops.

If you are doing any final treatments for fruit diseases, pay close attention to the PHI on the product label. The pre-harvest interval determines how long after you applied that product that you may harvest the crop. This is especially important to pay attention to as many varieties of orchard crops as well as grapes are maturing and nearing harvest.