crops

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.

Snow and Freezing Temperatures Bring Harvest Challenges in Agronomic Crops

Although it is not necessarily a common issue that we tend to worry about in this area, it does happen; that issue being snow accumulation occurring before crops are harvested. Obviously, this is not a new issue for those who may be dealing with snow covered crops but let this serve as a reminder of some considerations for harvesting crops this time of year.

One of the most important drawbacks of harvesting a crop this far past prime harvest season is that there will be a yield reduction. A study was done by the University of Wisconsin on the average yield loss in corn, when left in the field through winter. The study was reported on a monthly basis and showed that corn that was left in the field until January or February averaged a yield loss of 35%, per month. Now there are a few factors to consider for yield loss. One of the major factors is lodging. Lodging, or breakage of the stalk below the ear or pod, results in harvesting difficulties, pest, and disease problems, as well as grain loss due to ear or pod drop. Another factor resulting in yield reduction is the grain getting wet and then freezing. Repeated freezing and thawing can be problematic, especially in soybeans. Soybeans are prone to pod split and seed shatter. In corn, the wet husks can stick to the ear, leading to mold concerns and difficulty cleaning the grain properly. Additionally, leaving the grain out in the field leaves it open to wildlife feeding. Wildlife feeding, along with the other mentioned yield reducing factors compounded together can lead to significant yield losses.

Asides from yield loss, another issue that comes up when harvesting grain this time of year is the stress it can put on the equipment. It is important to get the combine settings right when harvesting frozen grain. It is also important to take care of preventative maintenance, as well as fixing appropriate repairs before running the combine through a frozen field. Combines can run in those conditions but running through a frozen and snowy field is not the easiest on them when looking at wear and tear.

Another important factor to consider is the soil. When you run a combine and a grain cart over wet, cold soil, compaction and rutting will happen. It is best to be patient and wait for a time when either the soil is frozen enough to be on, or the soil is dry enough to reduce compaction chances. The more likely of those situations is the soil freezing, as rarely do we have dry soils in the winter. Compacting and rutting the soil will result in problems for many years down the road. Out of all of the other impacts of winter grain harvest, the impact on the soil should be the one that you give the most consideration to. Severe compaction of your soil, as a result of attempts to harvest a corn or soybean field, likely with large yield losses already, can really hurt the productivity of the soil.

There is a choice to be made: try to salvage what yield you can this year by getting out in rough field conditions or wait for the ground to freeze and then harvest the crop, with minimal impact on the soil. Be patient and be willing to wait for the right conditions to get grain harvested and be willing to accept the hit on yield. Yes, a hit on yield is never easy to take, but a hit on long term field productivity is an even harder hit. Obviously, the situation calls for you to choose between the lesser of the evils, so while it may be something you have to deal with this year, have it in mind to do what you need to do to avoid the situation in the future.

Field Management Considerations Post-Harvest

As crops are being harvested, and fields are being prepped for the winter, there are several field management decisions that need to be considered. It is important to note that there is no singular correct management plan. Different approaches to field management will fit some farms better than others, it all depends on the goals you have set for your farm based on your management strategies.

Dealing with residue in the fall will help to avoid issues in the spring. Some issues that are encountered in spring while planting include attaining good seed-soil contact or disease issues due to a field not drying out. Another issue that can arise from improperly managed residue is large populations of slugs that can decimate young seedlings. Sanitation of the field and intensive management of residue can help to break up insect pest life cycles as well as disease cycles.

Residue management is a major aspect of post-harvest field treatment. The residue that we are concerned with is the chaff and stalks that are left after grain harvest. There are two ways to look at this residue. On one hand, the residue can act as a mulch that lessens the impact of rain falling on the soil, lessen the amount of erosion, help to retain soil moisture, and add organic matter and nutrients back into the soil. On the other hand, residue can help to over winter problematic insects, act as inoculum for diseases and slow soils from warming up and drying out in the spring.

The decision on how to manage residue comes out of your tillage and field management plans. In a no till or conservation tillage system, residue is considered more of a benefit to the field and left mostly as is. In a more intensive tillage system, residue is incorporated and broken up to influence a more rapid breakdown. There are benefits, as well as drawbacks, to both of these systems.

In an approach focused on conserving the residue, as previously stated, there are several benefits when looking at soil health and soil management. Conversely, the risk for insects to over winter and for diseases to carry over is also greatly increased. If there are fields on your farm with histories of diseases or insect problems, consider looking at how you have been managing the crop residue. If you would like to maintain your current conservation tillage systems, but reduce the risk of disease and insect infestations, using different tillage tools, such as vertical tillage, may be of interest to you. Using a vertical tillage tool serves several purposes. One is that it helps to chop up and spread out the crop residue. These tillage implements also often kick the soil up in a way that covers up a considerable percentage of the residue. This is important because covering the residue with soil will help to increase the rate at which decomposition occurs.

This approach, aimed more towards conservation tillage, may be of interest to those who have been involved with more intensive tillage. Intensive tillage and turning of the soil certainly results in a faster breakdown of crop residue. However, this tillage system leaves more soil exposed and can result in more wind and water erosion. Finding a system that can appropriately manage the crop residue while also maintaining some form of soil structure and improving soil health, will not only help the crops from year to year, but will also increase the sustainability and productivity of your soil.

Integrated Pest Management Considerations for Stored Grain Crops

Integrated pest management of a crop should not stop after it has left the field. The last thing that you want to have happen is for a crop, that you worked hard all summer to get to harvest, to be lost due to poor management while it is being stored in the bin. It is important to realize that storage of grains will not improve the quality of the grain. The quality of the grain will be at its best immediately after harvest. The goal of bin storage is to protect and maintain that quality.

Before putting grain in the bin, there are several steps that you should take to prepare the bin for new grain. One of the most important steps to take is to thoroughly clean the bin to remove any old, previously stored material from all components of the grain bin system. This includes the augers, fans, and the bins themselves. If you can tell what grain was last stored in the bin, it still is not clean enough.

While cleaning the bin, take time to make sure that the bin is sealed correctly and that the seals are not failing. A common area for a seal failure to cause damage is at the base of the bin where the bin rests on its cement base. This area is just one spot where moisture can enter the bin and cause significant spoilage. Also make sure to check the seals around doors and hatches. Screens should also be in place on roof vents to prevent larger animals from entering the bins. Aside from keeping a grain bin dry, keeping it sealed appropriately will also prevent the entry of insects, birds, and rodents.

Grain bin sanitation should also extend to the areas around the outside of the bin. At a minimum, at least 10-15 feet around the outside of the bin should be kept clean. This includes keeping it mowed and cleaning up spilled grain. Leaving favorable habitat and a food source intact that close to the bin is essentially creating a refuge for many of these pests. Not doing anything to prevent this is asking for trouble. Keeping this area cleaned up and maintained will prevent pest populations from building up within such a close proximity to your bin.

Some common insect pests that are found in grain bins include: flat grain beetles, saw-toothed grain beetles, red flour beetles, and Indian meal moths, just to name a few. The challenge with these insects is that they, as well as their eggs and larva can be harbored in old debris and grain remnants, hence why bin sanitation is so important. There are several preventative insecticides that can be added to the grain while putting it in the bin, as well as preventative products that can be added as a top dress after the bin is full. Fumigation, although not used as frequently as it once was, is also an option for insect management. As with any pesticide, the label is the law. Make sure to read and follow the label and use as directed.

Management of the bin while there is grain being stored is also important when considering pest management and grain quality control. Aeration will help to keep grain dry as well as disturb insects that may have made their way into the bin. Temperature monitoring is another way to manage grain quality, both from moisture and insect management perspectives. Keeping the grain bin at the appropriate temperature will prevent moisture from being drawn into the bin. It can also slow down or altogether prevent insect life cycles from repeating. Insects typically require certain amounts of heat units to progress from one life stage to the next, and if that can be slowed down or prevented, this lessens the need for chemical treatments.

It is important to realize that relying only on chemical options for insect management can be ineffective and costly. Without implementation of other integrated pest management strategies, chemical treatments are going to hurt your bottom line. It is essential to work strongly on the prevention aspects of grain bin pest management, rather than focus all your time, money, and effort on the reactive treatments. An ounce of prevention is worth its weight in gold by the time you are ready to move the grain out of the bin. Employing integrated pest management strategies into your grain storage systems can result in cost savings, from less reliance on chemical treatment, and better overall product quality.