Wayne County IPM Notes, May 3-7, 2021

Agronomic Crops

Mycelial growth on the crown of an alfalfa plant due to infection by Sclerotinia Crown Rot.

Generally speaking, the crop that we are most interested in at this point of the year is alfalfa. The corn and soybeans may have been planted, and in some areas, may be starting to emerge. The main concern in alfalfa in terms of insect pests is the alfalfa weevil. This year, it is especially problematic due to increased GDD accumulation. The early warm temperatures pushed us to about two weeks ahead of where we were last year in terms of our accumulated heat units. This is reflected in the progression of the alfalfa weevil, not only in size, but in number. Most fields were not over threshold, but certainly showed weevil damage and the weevils that were feeding ranged from 1st to 3rd instar.

While scouting alfalfa fields, its important to inspect the entire plant. The prolonged cool and wet weather that we have been experiencing has been perfect for development of Sclerotinia crown and stem rot in alfalfa and clover fields. It can be easy to confuse this disease as winter kill, but further inspection of the plant, especially near the crown can reveal white, mycelial, cotton like growth. You may also find sclerotia in or on the stems and crown. Once the weather warms up and fields dry out, this disease will likely stop progressing, and some infected stands may recover and produce sufficient yields in subsequent years. Keep in mind that those sclerotia will remain in the soil for many years waiting for perfect conditions to start the disease cycle again.

Vegetable Crops

            With the cold temperatures extending into our early growing season many growers with high tunnels are using heat sources such as wood burners and gas stoves to keep their high tunnels warm. If you are doing this, please make sure your vents are clear and that all of the exhaust, fumes and smoke are making their way out of the tunnel. Double check to make sure chimney pipes are snug and the joints are not loose. Plants, especially tomatoes, are very sensitive to ethylene gas, a by-product of burning and when the smoke or fumes from the stoves are making it back into the tunnel, the plants are exposed to the ethylene for prolonged periods of time. Plants exposed to ethylene will show signs of epinasty, or a downward spiral of shoots and curling leaves, as well as blossom abortion.

Epinasty in tomato due to ethylene exposure.

Other than vegetables in high tunnels, some cole crops and lettuce are planted. Onions and fall planted garlic are also handling this cool wet weather with relative ease. As a word of caution, wet soils and cold temperatures do not equate to great growing conditions for both transplants and direct seeded crops. Some crops handle it much better than others. For crops like summer squash, peppers, and tomatoes, it would be wise to hold off for a bit longer be fore attempting to get them in the ground.

Small Fruit and Orchards

            Apples are at petal fall. Peaches are at petal fall and, in some cases, shuck split. No CM or OFM concerns at this point in the orchards. We did observe some frost or freeze damage on some apple blossoms, but there are more than enough healthy blossoms to cover any loss from the freeze that occurred.

Blueberries are in full bloom and have no concerns at this time.

 

Strawberry bloom with a dark center. The dark center is the dead part of the bloom that would grow into the berry.

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. They will still put on new blooms, but do not expect large yields from early season strawberries.

Grapes also experienced some damage due to the cold temperatures. Currently, grapes are around the bud burst stage. Some buds that were exposed to the cold have died; others look damaged. In another week or so, we will be better able to tell the extent of the damage that occurred to the grapes.

Managing Fruit Trees and Horticultural Crops During Prolonged Exposure to Subfreezing Temperatures

I know many of us enjoyed our warmer than average March with no snow, however, that has come around to be quite problematic. That kind of weather in March encouraged rapid progression of our flowers, fruit trees and other plant species, which had given us a spectacular show of spring blooms and flowers. The plants responded to the above average number of growing degree days that they accumulated and began their flowering, budding, and progressing through developmental stages and reproductive processes. The flowers and buds are the most important part of the plant when we consider fruit production. They are also the most delicate and vulnerable part of the plant.

So, what can be done to protect your plants? The challenge here is that our forecasted low is 25° F, with almost 12 hours forecasted to be below freezing and 6-8 hours forecasted to be in the 20’s. This is not just a light frost, but rather a hard freeze. There are a few steps that you can take to try to protect the plants, and some of these steps can be better utilized on a small scale, while others are better utilized on a larger scale.

On a smaller scale, simple actions like covering the plants with a sheet or some kind of fabric can help insulate them. This helps trap some of the warmer air from the ground around the plant and keeps the plant from being directly exposed to the colder air. It may also be of interest to protect the crown of the plant. This freeze may be severe enough to damage the foliage, but you can take steps to protect the crown and the roots by mulching with straw, leaves or wood mulch around the plant to keep the warmer air from the ground around these vital parts of the plant to keep it alive. Basically anything that you can do to insulate the plant, conserve the heat in the ground, and shield it from the cold air, will be beneficial to the plant and give it a better shot at making it through the night.

Adding a strand of Christmas lights (not LED) under the sheets covering your plants can help add a little extra heat to keep the ambient temperature a little warmer. Make sure that the lights are not touching the covering material and keep the covering material off of the plants. If the covering material is sitting directly on the foliage, that is defeating the purpose of having it there in the first place. Use stakes to keep the sheets or other covering materials just above the foliage. This will prevent the cold temperatures from being conducted onto the plants.

Watering the soil can also keep the immediate area around the plant a few degrees warmer. A wet soil is going to hold heat better than a dry soil. Even a few degrees can make a big difference. With single plants or with small enough shrubs or tree seedlings, an overturned bucket serves the save purpose as the sheets or coverings. Just remember, as soon as the sun comes up the next morning, you will want to remove whatever coverings you have to allow the plant to be exposed to the sunlight and begin to warm back up.

If you have a home orchard, it can be challenging to work with due to the size of the trees. One option is to hang the trees with the old-fashioned Christmas lights, however these are getting harder to find. They need to be the big bulb type, the newer LED Christmas-tree lights won’t work since they’re cool burning and won’t give off sufficient heat. You can improve the protection by also covering with a blanket or tarp.

Another option is to turn a sprinkler on your trees just as the freeze begins, to coat them with ice. Although it seems counterintuitive, the ice will protect the tree because the temperature beneath the ice will not drop below 32 degrees. For this method to work you will need to keep the sprinkler on until the temperatures rise above freezing. If you plan to use this method of frost protection and the cold temperatures last for a while, monitor to ensure that you are not creating a flood somewhere else.

On a larger scale, orchard growers and those with small fruit have big challenges. They are dealing with a lot of plants and trees over a big area. Some orchards use frost fans to try and protect the crop. Frost fans work by utilizing warmer/drier air from the ‘inversion’ layer to create air movement at the fruiting/flowering height in orchards on still cold nights—preventing damage to flowers, soft tissue, and fruit. Some orchards utilize water sprinkler systems to actually create a layer of ice on the trees. The key to using water is to continually use it to form clear ice. Clear ice means that an endothermic reaction is taking place and the warmth of the plant is being trapped inside it. If the ice starts to become cloudy, the plant is losing heat and damage can occur. Spraying water must continue the entire time the freeze event is taking place, and the sprays must keep going from before there is a freeze event that would damage the fruit until the ice is completely melted from the tree after the event. If the water stops spraying on the clear ice, it goes from being endothermic to exothermic, and the heat loss and ice will damage the fruit.

In some cases, burn barrels and smudge pots are placed around an orchard to add heat in the hopes of keeping the temperatures at, or above freezing. Unfortunately, it can take roughly 30-50 heaters per acre to effectively protect the trees. In some cases, if you are working with just a few trees, a strategically placed burn barrel can do the trick. Keep in mind that if you decide to use any type of heater you need to be extremely cautious using them.

Minimizing damage and losses requires knowledge of weather conditions and how to mitigate weather extremes. Just as important is having a knowledge of plant hardiness. Some plants will do just fine with this cold weather. Others may appear to be killed off but may regrow from the roots or the crown, even though the foliage appears dead. The important thing here is to not be over-reactive. Give the plants time to recover. Plants can be remarkably resilient. If you see signs of frost damage, do not prune off the affected parts or dig up the plant immediately. Wait until the weather warms up to see whether new leaves sprout. You may see healthy new growth at the base of the plant, at which point you can prune out the damaged parts.

Hoping for the best and doing nothing will not result in any positive outcomes, so take this opportunity to at least cover the plants that you can and give them a fighting chance to make it through the cold.

Dormant Fruit Tree Management

Fruit tree care, and management, does not simply stop when the leaves fall off the tree late in the year. Fruit tree care is a year-round job and in order to get the best performance out of your fruit trees, its important that certain tasks are done at the right times.

With the trees dormant now, it is a good time to look at some disease management options. When we talk about dormancy, we are looking at the time frame between when the tree drops the leaves in the fall and when buds begin to swell in the spring. With diseases such as peach leaf curl, applying a fungicide while the tree is dormant is recommended. Thorough and complete coverage of the tree is needed to ensure complete control. Typically, the top 3-5 feet of a tree are hardest to reach and this is the area in which we see the fungicide lose efficacy, either due to low coverage or just simply not being reached by the application. Although applications are most effective when applied in the late autumn after leaf fall, its important to apply the fungicide before the buds on the trees start to swell, which will start to happen before too long.

There are other dormant sprays to help control diseases such as Phytophthora crown/root/collar rot or bacterial spot/canker, and these are typically applied before growth starts in the spring. There are also sprays, for example, copper products for fire blight, that are applied right before growth starts in the spring, and when temperatures are above 45° F.

Dormant oil is regularly used on apple, pear, and plum trees to aid in control of scale and aphid pests, at a rate of 2%, which means 2 gallons of horticultural oil per 100 gallons of water. This should be made as a dilute application, with plenty of water so that all bark is treated. As the word “dormant” implies, this spray should be applied before the buds swell or before new growth (green tip stage) starts in the spring. If applied after growth starts, the new tissue can be damaged by oil at this rate. Application should be done when temperatures have been above freezing (above 35 degrees F) the day before the application and when the weather forecast calls for non-freezing temperatures for at least 24 hours after application. For this area, usually late February to early March is a good target period. Oil can also be used for control of mites, but for best control of mites, it is more effective if application is delayed until late in the “delayed dormant” stage. When oil is applied at the half-inch green bud stage or no later than the tight cluster bud stage, the rate can be dropped to 1%, meaning 1 gallon of horticultural oil per 100 gallons of water. Oil at this time should still be applied in dilute form so that all of the bark surface is treated. An important note: for all fruit crops, if liquid lime-sulfur is used, it should not be sprayed with, or in close timing (~1 week) with an oil spray as tissue damage can result.

Regardless of your level of involvement with chemical application or the scale of the operation, the most important thing for you to do is to read the product label. The label is the law. More information on products and recommendations can be found in the “Midwest Fruit Pest Management Guide”.

Chemical control options are not the only disease management tool that you should use. Cultural control and sanitation around the fruit trees is also important. When referencing “cultural” controls, this refers to the management techniques that are implemented when working with a crop and the associated diseases and pests. A lot of diseases over winter on leaf litter and dropped fruit on the ground. As a disease management strategy, implementing a cultural control practice of cleaning up and disposing of leaf litter or fruit residue can reduce the amount of inoculum around the tree, in turn reducing the disease pressure from those diseases. Pruning is also an important part of winter management and likewise, as you prune, it is important to burn or dispose of the pruned branches. During winter pruning you can target diseased branches and help reduce the impact of diseases, such as fire blight or black knot, in your trees.

Another opportunity to stay busy with fruit trees is right around the corner. Now is the time to get your fruit tree orders together and be preparing to get the trees in the ground in March or April. Allowing the roots to get established in soil that isn’t frozen, while temperatures are still cool, and while the ground still has adequate moisture, will help avoid stress on the tree when the top growth is initiated by longer days and warmer temperatures.

Fruit trees typically need to be fertilized once a year in early spring before growth starts. It is very important to do a soil test to determine accurate fertilizer recommendations. Generally speaking, a common fertilizer recommended for fruit trees is one with an analysis of 12‑12‑12 or 10‑10‑10. However, fertilizers of other analyses can also be used. The rate of application needs to be adjusted based on soil test analysis and recommendations. More information on specific requirements, recommendations and guidelines can be found in the “Midwest home Fruit Production Guide” publication by The Ohio State University.

Branching off of fertilizing, competition of nutrients and moisture is one of the main reasons to control and limit the amount of vegetation under fruit trees. Reducing this vegetation also limits the favorable conditions and habitat available for diseases, insects, and rodents. Weeding is not a fun job, but nonetheless, a year-round one.

Hopefully, this is enough to keep you busy until the warm days arrive. The trees will be budding and blooming before we know it. If you are interested in purchasing any of the publications mentioned in this article, give your county OSU Extension Office a call, or visit extensionpubs.osu.edu to find a full listing of all of the OSU Extension publications.

Dormant Fruit Tree Management

Fruit tree care, and management, does not simply stop when the leaves fall off the tree late in the year. Fruit tree care is a year-round job and in order to get the best performance out of your fruit trees, its important that certain tasks are done at the right times.

With the trees dormant now, it is a good time to look at some disease management options. When we talk about dormancy, we are looking at the time frame between when the tree drops the leaves in the fall and when buds begin to swell in the spring. With diseases such as peach leaf curl, applying a fungicide while the tree is dormant is recommended. Thorough and complete coverage of the tree is needed to ensure complete control. Typically, the top 3-5 feet of a tree are hardest to reach and this is the area in which we see the fungicide lose efficacy, either due to low coverage or just simply not being reached by the application. Although applications are most effective when applied in the late autumn after leaf fall, its important to apply the fungicide before the buds on the trees start to swell, which will start to happen before too long.

There are other dormant sprays to help control diseases such as Phytophthora crown/root/collar rot or bacterial spot/canker, and these are typically applied before growth starts in the spring. There are also sprays, for example, copper products for fire blight, that are applied right before growth starts in the spring, and when temperatures are above 45° F.

Dormant oil is regularly used on apple, pear, and plum trees to aid in control of scale and aphid pests, at a rate of 2%, which means 2 gallons of horticultural oil per 100 gallons of water. This should be made as a dilute application, with plenty of water so that all bark is treated. As the word “dormant” implies, this spray should be applied before the buds swell or before new growth (green tip stage) starts in the spring. If applied after growth starts, the new tissue can be damaged by oil at this rate. Application should be done when temperatures have been above freezing (above 35 degrees F) the day before the application and when the weather forecast calls for non-freezing temperatures for at least 24 hours after application. For this area, usually late February to early March is a good target period. Oil can also be used for control of mites, but for best control of mites, it is more effective if application is delayed until late in the “delayed dormant” stage. When oil is applied at the half-inch green bud stage or no later than the tight cluster bud stage, the rate can be dropped to 1%, meaning 1 gallon of horticultural oil per 100 gallons of water. Oil at this time should still be applied in dilute form so that all of the bark surface is treated. An important note: for all fruit crops, if liquid lime-sulfur is used, it should not be sprayed with, or in close timing (~1 week) with an oil spray as tissue damage can result.

Regardless of your level of involvement with chemical application or the scale of the operation, the most important thing for you to do is to read the product label. The label is the law. More information on products and recommendations can be found in the “Midwest Fruit Pest Management Guide”.

Chemical control options are not the only disease management tool that you should use. Cultural control and sanitation around the fruit trees is also important. When referencing “cultural” controls, this refers to the management techniques that are implemented when working with a crop and the associated diseases and pests. A lot of diseases over winter on leaf litter and dropped fruit on the ground. As a disease management strategy, implementing a cultural control practice of cleaning up and disposing of leaf litter or fruit residue can reduce the amount of inoculum around the tree, in turn reducing the disease pressure from those diseases. Pruning is also an important part of winter management and likewise, as you prune, it is important to burn or dispose of the pruned branches. During winter pruning you can target diseased branches and help reduce the impact of diseases, such as fire blight or black knot, in your trees.

Another opportunity to stay busy with fruit trees is right around the corner. Now is the time to get your fruit tree orders together and be preparing to get the trees in the ground in March or April. Allowing the roots to get established in soil that isn’t frozen, while temperatures are still cool, and while the ground still has adequate moisture, will help avoid stress on the tree when the top growth is initiated by longer days and warmer temperatures.

Fruit trees typically need to be fertilized once a year in early spring before growth starts. It is very important to do a soil test to determine accurate fertilizer recommendations. Generally speaking, a common fertilizer recommended for fruit trees is one with an analysis of 12‑12‑12 or 10‑10‑10. However, fertilizers of other analyses can also be used. The rate of application needs to be adjusted based on soil test analysis and recommendations. More information on specific requirements, recommendations and guidelines can be found in the “Midwest home Fruit Production Guide” publication by The Ohio State University.

Branching off of fertilizing, competition of nutrients and moisture is one of the main reasons to control and limit the amount of vegetation under fruit trees. Reducing this vegetation also limits the favorable conditions and habitat available for diseases, insects, and rodents. Weeding is not a fun job, but nonetheless, a year-round one.

Hopefully, this is enough to keep you busy until the warm days arrive. The trees will be budding and blooming before we know it. If you are interested in purchasing any of the publications mentioned in this article, give your county OSU Extension Office a call, or visit extensionpubs.osu.edu to find a full listing of all of the OSU Extension publications.

Storage of Fall Fruit and Vegetable Crops After Harvest

As the growing season comes to a close and crops are harvested this fall, many growers may look at storing some crops to sell throughout the winter and early spring. Some commonly stored vegetables include potatoes, onions, and garlic. Most of the stored fruit crops, in terms of long-term storage, is focused on apples and pears. Proper care and storage of these products can provide additional income throughout the winter months when other crops are unable to be locally grown and sold. These storage practices may be useful for those just simply looking to store crops for home use as well.

Delving into the practice of storing vegetable crops, to start out, you want to make sure that you are only attempting to store what would be considered “firsts” or products of the highest quality grade. Products that have blemishes or defects are not suitable for long term storage. Attempting to work some of the “seconds” into your stored products can be risky and may result in a higher loss of product during the storage process. Some other pointers before putting away crops over winter include finding varieties that are better suited for winter storage, planting the crops so that at the end of the season you are harvesting the crops in their prime (which is when they will store best), and having an area where you can provide suitable conditions for storage of the desired crops. Another important step in the process is called curing. Curing is a process that allows the skin to become more durable which helps to extend shelf life. Potatoes cured at 60-70 degrees F for 4-5 days can be kept for 4-5 months. Onions need cured for approximately 2 weeks, where they need to be spread out and dried until the outer skin becomes papery and dry. Garlic is cured in a very similar manner as onions. Winter Squash and sweet potatoes that are cured for 10-14 days at 75-80 degrees F can be stored for several months.

Appropriate storage conditions are another major factor of being able to keep vegetables long term. Potatoes are best kept at between 40-50 degrees F with higher humidity and no light. Large temperature fluctuations or too much light can induce sprouting. Sweet potatoes also store best in higher humidity, and with temperatures between 45 and 60. Pumpkins and squash store better in low humidity environments. Garlic is stored best at temperatures near 35-40 degrees F and with low humidity and no light. Onions storage temperatures are recommended at around 35 degrees F with moderate humidity. These areas also need to be well ventilated to prevent excess moisture from building up and to provide the area with “clean”, fresh air. Storage areas should not only be set up to allow for good airflow, but they should also be set up in a way to allow you to inspect the crops at various times throughout the winter. It is important to watch the stored crops closely and remove any decaying products as soon as possible. The longer a decaying fruit or vegetable is allowed to be there, the higher the risk of others being affected.

Apple and pear storage is not too different from vegetable storage. They too need to be harvested at the correct time to prevent them from becoming over ripe in storage. Too, they need to be in a cool and well-ventilated space with no light. The ventilation also prevents the buildup of ethylene, which helps to slow down the ripening process. Ethylene increases the speed at which the fruit ripens.  It is important to note that these storage spaces should not drop below freezing. Freezing temperatures followed by above freezing temperatures will damage fruit and vegetables and make long term storage nearly impossible. Apples and pears also need checked to make sure that there is no fruit going bad. The saying goes “one rotten apple spoils the whole barrel” and that is true for both fruits and vegetables. When fruits and vegetables are harvested at the correct time and given good storage conditions, they can be enjoyed many months after the growing season has wrapped up.

Soil Management in Specialty Crops

Specialty crops, such as fruits and vegetables, require special considerations in terms of soil management and fertility. As the growing season winds down and more crops are harvested, you may feel as though you have nothing left to do except wait to start it all over again in the spring. Soil that is continuously cropped with fruit and vegetable crops can become depleted of key nutrients rather quickly and, now is the best time to work on addressing issues that you may have with your soil. Additionally, addressing issues with your soil may even resolve other issues such as disease and weed pressure.

An important aspect of determining whether you have areas that need addressed or even how to address them is to take soil samples. Soil sampling is the most direct way to understand what is going on in your soil. Most soil test will give you the results for the macro nutrients phosphorus and potash, which are used in the highest amounts by the plants. They will also usually include the secondary nutrients calcium and magnesium, that are used to a lesser degree. Soil test results may also show you your soil pH, organic matter percentage and the cation exchange capacity. All of these factors are important in making a decision on your soil fertility and soil management strategies.

Before diving into any of the topics surrounding soil management and soil fertility after a growing season, it is first important to understand the basics of nutrient uptake by the plant. The roots are the main pathway in which nutrients are transported into the plant. In order for this to occur, the nutrients must be in a form in which they are mobile. The nutrients are mobile in the soil when they are broken down or dissolved into the soil solution, at which point, the roots are able to take them in and move them throughout the plant.

The process of a nutrient breaking down or being dissolved in the soil solution takes time. That is one of the major reasons to address soil fertility concerns in the fall. Being able to apply certain nutrients, such as potassium, in the fall and allowing them all winter to break down and become available to the plant is optimal. Certain nutrients like nitrogen, you can apply right before planting, as nitrogen is available to the plant for uptake rather quickly after application. Regardless of whether you are addressing soil fertility issues in the fall or the spring, it is important that you do so with careful consideration for nutrient loss. Nitrogen is a very mobile nutrient and can be lost through several pathways fairly easily. It is also of your best interest to make soil amendments based on a recent soil test report. How else would you know what to apply or how much? Knowing what your soils already have and how to make them better will not only prevent over application that could lead to nutrient runoff, it will also save you money. Over buying and over applying nutrients is doing nothing but pouring money down the drain.

Another important factor of your soil management decisions should be based on your soil pH. Each crop type will have a more specific optimal pH, however, in general a pH between 6.0 and 7.0 is recommended for most crops. Being able to maintain an appropriate pH level will also help to influence plant growth due to optimal nutrient uptake. At a pH of approximately 6.2-7.3, nutrient availability is at its highest. With a pH any lower or higher than this range, nutrient availability sharply declines. So even if you were applying the correct amount of nutrients or over applying because the plants weren’t responding to the fertilization, having a pH outside of the optimal range is likely preventing the nutrients from becoming available for plant uptake.

Soil fertility is one of the biggest factors that influence crop yield. Foliar feeding has its place with specialty crops; however, it should not be relied on to address issues with crops that are due to poor soil nutrient management. Excessive foliar feeding, especially with nutrients that are not mobile in the plant, is costing you money that you are not getting a return on. If you are having issues year after year that you are associating with soil fertility issues, address the issues in the soil. Remember that the roots are specifically there to take up water and nutrients. Not only will improved soil fertility help with crop yields, it will also improve overall plant health. A healthy plant is a strong plant, and a strong plant stands up better to disease and insect pressure.

Take the time this fall to take soil samples. Work with your local co-op or soil lab and address the nutrient concerns in your soil. Your soil is worth your time and investment. You should put in the effort to take care of the soil and consider even improving it and leaving it in a better condition for future generations. I heard it said once that despite all of our accomplishments, we owe our existence to a six-inch layer of topsoil and the fact that it rains. Take care of your soil and it will take care of you.

Wayne County IPM Notes from September 20-26

Wayne County IPM Notes

(From the Week of September 20 – September 26)

Frank Becker, OSU Extension Wayne County

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

Wayne County IPM Notes

(From the Week of September 13 – September 19)

Frank Becker, OSU Extension Wayne County

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, once 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.

Wayne County IPM Notes from September 6 – 12

Wayne County IPM Notes

(From the Week of September 6 – September 12)

Frank Becker, OSU Extension Wayne County

Vegetable Pests

After seeing the adult butterflies flying amongst cabbage, kale, and broccoli plantings for the past week or so, I am now finding imported cabbageworms feeding on these plants. Scouting your latest plantings of cole crops is recommended to make sure that these worms 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.

Corn earworm numbers continue to increase in our traps in Wayne County, as well as across the state. Since late planted sweet corn has green silks and is an attractive crop for the moths to lay their eggs on, we typically see an increase in moths this time of year in, or near, sweet corn plantings. This time of year, field corn may be responsible for the large increase in moths, as the lack of green silks leads them to find alternative sites to lay their eggs.

Vegetable Diseases

            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

All of the traps out for codling moth and oriental fruit moth continue to decline, and in some cases are dropping to no moths being found in the traps.

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

            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.

Wayne County IPM Notes for August 30 – September 5

Wayne County IPM Notes

(From the Week of August 30 – September 5)

Frank Becker, OSU Extension Wayne County

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.