weather

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

Agronomic Crops

Cut alfalfa field in Wayne County.

The weather was very cooperative this week and a lot of forages were cut, and field conditions were right to either get fields ready to plant or start to get seeds in the ground.

In the interest of alfalfa growers, we have been paying close attention to the alfalfa weevil larvae and their development. The weevil larvae are forming cocoons and pupating.  Typically, we only experience a single generation of alfalfa weevil per season, however, given the early development and continuation of above average temperature, there is the chance of seeing a fairly substantial 2nd generation. This is problematic for a few reasons. First off, if we continue to see hot and dry conditions, that in itself will stunt regrowth on cut alfalfa. Additional feeding by young 2nd gen weevil larvae on stressed alfalfa regrowth can either severely delay 2nd cutting or if the infestation is significant enough, total loss of 2nd cutting.  Typically, by this point in the year, we begin to move on from alfalfa weevil scouting and turn our attention to the Potato Leaf Hopper, however, this year we may be dealing with both at the same time.

We are not yet scouting any corn or soybeans; however, we expect that we will begin to see more of those acres planted and have relatively rapid germination due to increasing soil temperatures. A few timely rains can help to push these crops germination as well. Soil temperature and GDD Accumulation

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.

Wayne County IPM Notes for the week of May 10 – May 14

Agronomic Crops

            This week again, we saw sustained activity and feeding from the alfalfa weevil. At this point, we have started to observe some of the weevil reaching later stages of development and beginning to pupate. In cases where there is a poor alfalfa stand, the weevil damage is more severe as compared to feeding in a full, healthy stand.

Alfalfa weevil cocoon. Tommy Becker photo.

            As the alfalfa continues to grow taller, we also noticed some lodging where after heavy rains, the alfalfa began to lay over. This is not a major concern, but just something to be aware of.

            While driving around the county, we did observe some corn fields that were planted, and the corn plants are beginning to emerge. In our travels we did not see any soybean fields, although, we have heard reports of some soybeans emerging as well.

Vegetable Crops

            Remember to keep your high tunnels ventilated and not too wet as not doing so can lead to conditions that can create the perfect environment for diseases. As such, we began to observe high tunnel tomatoes with early blight. Low humidity, consistent air movement and proper plant spacing can all help to avoid experiencing certain foliar and root diseases.

Early flea beetle feeding on young cole crops.

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 before attempting to get them in the ground.

We did note some frost damage to potatoes that were emerging. We also spotted some flea beetles on cole crops this week.

Sweet corn that was planted early is somewhere around the V2 mark, standing about 3-4” tall. Given some warm temperatures and sunshine, the corn will really take off.

Small Fruit and Orchards

            Apples are at fruit development. Peaches are at shuck split. No CM or OFM concerns at this point in the orchards.

Blueberries are in petal fall and are setting fruit. We are starting to see Phomopsis blight in some blueberry bushes.

Ripening “plasticulture” strawberries. Tommy Becker photo.

Raspberries are getting ready to bloom and overall seem to be coming along just fine.

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. Early varieties of plasticulutre strawberries that were covered and protected from the cold are setting fruit and beginning to ripen.

Grapes also experienced some damage due to the cold temperatures. Currently, grapes are around the bud burst stage, and some are at the 4-8” shoot stage. Some buds that were exposed to the cold have died; others look damaged. We are still waiting to see the full extent of the frost damage in many of our small fruit and orchard crops.

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.

Winter Injury to Forages, Wheat and Rye

Ohio is no stranger to a wide range of fluctuating winter conditions. After the recent spell of cold and snow in Ohio, we are now looking ahead to rain and warmer temperatures. While this relief from the winter elements may be appreciated by many, this flip of conditions can result in some challenges with our over wintering grain and forage crops.

Dennis Pennington, a wheat system specialist from Michigan State University shares some of the details on why crops such as wheat need the cold weather and why the break in cold temperatures can cause problems.

Pennington, on wheat states, “Winter wheat goes through a vernalization period where the plant hardens and adjusts to the colder winter temperatures. The hardening off period begins in the fall once temperatures at the crown (growing point, generally placed about 1-2 inches below ground surface level) drop below 48 F and continues as the temperature decreases. The hardening process causes a reduction in moisture content in the cells of the crown which slows growth processes and the accumulation of soluble carbohydrates, all of which help the plant to resist frost damage.”

Dennis goes on to discuss the hardening process, as he states, “The hardening process takes place over four to eight weeks and the level of hardiness is directly related to the soil temperature at the crown depth. Daylength also impacts hardiness, as shortening days in the fall induce wheat winter hardiness. Conversely, longer days in spring bring wheat out of hardiness. Cold tolerance is dynamic and can be lost if soil temperatures rise above the previous temperature that the plant hardened to. According to a study by D.B. Fowler from the University of Saskatchewan in 1982, if the crowns of the plants are exposed to warmer temperatures for as little as 50 hours, the cold hardiness can be decreased substantially. The loss of cold tolerance has several major implications.”

Winter wheat greening up in the spring. Some tip die-back is visible in this photo.

The two major implications that Pennington describes in his article are the following: First, if soil temperature decreases below the current level of winter hardiness, injury will occur. Secondly, once a crop loses winter hardiness, it will never reach the original level of hardiness and it will de-harden more quickly each time the soil temperature rises above the minimum survival temperature.

As pointed out by Pennington in his article, what you want to see is a steady line in the temperature, without large spikes in either direction. Whenever the temperature spikes up followed by a spike down below the original temperature, injury can occur.

Generally speaking, when looking at the crops that are over-wintering in the fields, snow melt can be a concern. Obviously, warm weather causes the snow to melt. Snow, however, serves as an insulator and can protect the crowns of plants against major swings in air temperature. Snow melting can also result in ponding in the fields. In cases where drainage is adequate, there should be little to no concerns, but where water persists, evident by ponding or high levels of field saturation, waterlogging may occur. Additionally, if the water persists, the crowns may absorb more water, which could be problematic should conditions become cold again as it would result in cell rupture when the water in the plant freezes and expands. Ice damage can also occur in areas where standing water freezes over dormant plants for an extended period of time, essentially suffocating them. There is really a wide range of problems that can occur when we have a significant amount of snow the melts off before we are safely out of reach of winters grasp.

An example of how far an alfalfa plant can be heaved out of the ground via several rounds of freeze/thaw cycles.

Another concern, especially in forages, is heaving. Now that the ground is exposed, should we get back into a freeze/thaw pattern, heaving could occur. Heaving occurrence can increase significantly in areas of fields where there is a lot of moisture, and with the recent snow melt, there are a lot of fields with excess moisture.

Getting closer to spring, these issues may not be anything to worry about, but certainly something to be aware of. Worrying about temperatures will do nothing to change them, and this area of crop production is unfortunately out of our hands but being aware of these concerns can help you assess damages should any occur. Getting out to scout alfalfa, wheat and rye fields in the spring is recommended, not only this year, but every year. Evaluating your fields as early as you can in the spring can help you make efficient and impactful management decisions and consequently, take action if warranted.