Acreage Reporting Deadline Looms

Lucas Clifton, Farmers First Services; LP33DE@yahoo.com

Many Delaware crops – including corn, grain sorghum, lima beans, soybeans and processing varieties of sweet corn and tomatoes – have an acreage reporting deadline of July 15 for crop insurance policies. Accurate acreage reporting and on-time reporting is important to an operation because:

1. The report is the basis for determining the amount of the insurance provided and the premium charged.

2. Once the deadline had been passed, changes may not be allowed to the acreage report.

3. The acreage report shows the crops you have planted, acreage prevented from planting, what ownership share you have in those crops, where the crops are located, how many acres you planted, the dates you planted them, what insurance unit they are located on, and the cultural practice followed (i.e., irrigated, double cropped, etc.). The more accurately these components are reported, the easier it will be to expedite possible claims in the future.

When reporting, make sure that your operation’s crop insurance and USDA Farm Service Agency reports are identical (you must provide written explanation of any differences). Also make sure that you receive and retain a signed copy of the reports that you file, as this is critical to correct any errors that may show up later.

About 8 to 10 weeks after you submit your acreage report, you will receive a Summary of Protection or Schedule of Insurance. This document summarizes your previous acreage report as it appears in the official records. Review it carefully to make sure that all entries are correct and match the copy of your signed acreage report that you initially provided to your insurance agent.

Differences between the summary and your signed acreage report can usually be corrected if you contact your agent and give notice of the error immediately upon receipt of the summary.

Excessive Rainfall on Newly Planted Soybean and Young Soybean

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

There have been numerous questions concerning whether soybean fields need to be replanted or not after the frequent and often excessive rainfall during June. The soybean plant has an amazing ability to compensate for inadequate stand density but in a large measure the ability to compensate depends on the uniformity of stand loss. With the recent flooding, we have seen several types of stand loss in Delaware fields. The first type results from either seedling emergence failure from seed death due to flooding; or, for already emerged plants, death of an established stand occurs from prolonged submergence or saturated soil. These events can be either localized in low areas in a field or in some cases for large portions of our relatively flat fields in the lower counties of Delaware. The proportion of the field affected can generally be calculated and a yield loss estimate determined since in this case the stand is essentially zero.

Another type of stand loss, we’ve seen is the loss of portions of rows, individual plants in a row, or scattered small areas that create a non-uniform loss in a field. For this type of loss, it becomes very difficult to determine the ultimate effect on yield. The larger the skipped area, the greater the probability that weed encroachment will occur and the lower the chance that the soybean plant’s compensation ability will be adequate to make up for the loss of stand. Uniform losses, unless very severe, will easily be overcome by the additional space (nutrient, sunlight, and water) each soybean plant has in which to grow.

I’ll go into what happens to a soybean plant when flooding occurs later in the article but first let’s go over some of the suggestions for what to do if there is a stand problem. Many of these and the explanation of what occurs during flooding come from Dr. David Holshouser, the Extension Agronomist at the Virginia Cooperative Extension Tidewater Agricultural Research & Extension Center. Dr. Holshouser discussed the impact of flooding in the last issue of Virginia Soybean Update, Vol. 14, No. 1. That issue and archived issues can be found on-line at http://blogs.ext.vt.edu/soybean-update/.

I think the most important decision involves the use of the rotary hoe on soils in many areas in Delaware where heavy rainfall after planting leads to crusting problems. This problem is even worse when planting on conventionally tilled soil that is low in organic matter or has minimal surface residue present. Almost everyone at one time or another has experienced crusting problems with soybeans so the tendency is to try to get back on the field as soon as possible to break up the crust to help seedlings emerge since they have already been severely stressed due to the heavy rainfall and possible flooding or saturated soil conditions. Stressed seedlings will have an even more difficult time emerging from crusted soil. What we need to remember is that if we get back on a field that is too wet, we will easily compact the soil either from the downward pressure of the tractor or equipment tires and from the action of the tillage equipment. Compaction will increase the stress on the crop, slow its recovery, and limit root development needed to help the remaining plants compensate for stand losses. So, the first rule to follow is to stay off the field until it has drained and dried enough to support equipment.

Next, evaluate the remaining stand to determine if it’s worthwhile to replant. Dr. Holshouser’s research indicates that after mid-June, soybean yield potential declines at the rate of about ½ bushel per acre per day of delay in planting. Research Bob Uniatowski and I did a number of years ago indicated that this decline accelerates as you move into July reaching about 1 to 1.5 bushel per acre per day in mid-July. This does not mean that on occasion a grower will find double-cropped soybean yields higher than full-season soybean yields. Late-season rainfall pattern and temperatures can dramatically improve or destroy double-crop soybean yield potential but on average we do see yields decline as planting date is delayed. What this means is that even if the current stand is below the ideal soybean population, those plants have a much higher potential yield than the seed that has yet to be planted. Try not to be over optimistic about the yield potential of replanted beans or pessimistic about the yield potential of your less than ideal soybean stand.

Stress such as weed competition, foliar burn from post-emergence herbicides, root restriction from compaction will add to the slow recovery of your soybean crop. For weed competition, we know we will need to apply some form of control to limit their impact on soybean yield potential. In particular if you are adding a tank-mix partner to glyphosate for Roundup Ready™ soybeans, choose that partner that will cause the least amount of foliar burn on the soybean crop. Be selective in choosing other partner material such as COC, NIS, and fertilizers to avoid the chance for foliar burn. Of course if you planted wide-row soybeans, you might consider cultivation for weed control but again do not get back on the field until it has dried out enough to support the equipment and the tillage practice without causing additional injury through compaction.

While walking your fields to evaluate the uniformity of the stand and the population count, dig up a few roots and inspect them for Bradyrhizobia nodules. If nodules are present, split some open and look for a pink color that will form as oxygen interacts with the nodule surface. If the inside is pink or red in color then the nodule is active. Black, green, or white nodules are inactive. If nodules are not present or are not active, you’ll want to recheck the field in a week or two to make sure the plants have either renodulated or the nodules have reactivated since the soybean plant depends on functioning nodules for a large proportion of its nitrogen. Another thing to do while walking the field and digging up a few plants here and there is to cut a few stems and roots open and inspect for any disease discoloration. If you suspect a disease problem, you may want to send some plants up to our plant diagnostician, Nancy Gregory in the UD Plant Diagnostic Clinic. Contact your county agricultural agent for information on forms and procedures.

There will likely be a lot of foliar fertilizer and possibly fungicides sold to help ‘kick-start’ the soybean crop back into rapid growth. I agree with Dr. Holshouser in his assessment that there is little advantage to using any of these products. The problem affecting the soybean crop from the excessive rainfall is the lack of oxygen (O2) to the roots, possible buildup of carbon dioxide (CO2) in the root zone, and the impact of ethanol toxicity from prolonged flooding. Once the soil drains enough that O2 reaches the roots again and the plants are able to begin photosynthesizing carbohydrate to support root growth, the crop will be able to obtain adequate nutrients from the soil.

Let’s next take a look at what happens to the plant during flooding or saturated soil conditions. There is limited research available on the long-term effect of flooding in soybean fields but it is thought that the impact will largely depend on the following factors: 1) the stage of development when the flood or saturated conditions occurred, 2) the duration of the flood or saturated conditions, 3) the temperature during and immediately after the flood, and 4) the rate of field drying after the flood.

What occurs during a flood is the depletion of soil O2 which causes photosynthesis to slow. Several days without O2 causes the plants to turn yellow, slow their growth rate, and possibly die. Some indirect effects can occur as well including reduced nitrogen fixation by the Bradyrhizobia bacteria located in nodules on the soybean root system, nutrient imbalances from disturbed root growth and function, and increased disease pressure.

Flooding Before Emergence
The greatest impact from flooding occurs on un-emerged soybean when the duration of the flood is greater than 24 hours, when soil temperatures are low, and when flooding occurs 2 or 3 or more days after seeds have imbibed water (imbibition is when seeds swell as they take up soil water and begin the germination process). Flooding that occurred one day after imbibition resulted in a 20 percentage point reduction in germination even after 48 hours of saturated conditions according to controlled research conducted during the late 1990s. This increased to a 33 or 43 percentage point reduction if the flooding occurred 2 or 3 days, respectively, after imbibition. The researchers found that the farther along the seed was in the germination process, the more susceptible they were to flood damage. Lower soil temperatures increased the damage. The researchers suggested that damage to the seed under brief flooding was primarily physical from seed membrane disruption/damage but with longer flood duration the injury was physiological from ethanol toxicity, O2 depletion, and CO2 build-up. In addition to a reduction in germination percentage, crusting can add to stand loss especially on worked ground low in organic matter or surface crop residue. Finally, for those seedlings that manage to emerge, there is an increased chance of seedling diseases resulting in an even greater stand loss and this is aggravated by the higher soil temperature we see at this time of year.

Flooding After Emergence
Soybeans can usually tolerate up to 2 days of flooding or saturated soil conditions but beyond this duration significant yield reductions can occur. Factors that affect the amount of yield reduction include the development stage of the crop at the time of flooding/soil saturation, the duration of the flood, the type of flood (stream overflow versus low land depressional flooding), temperature during the flood, the drainage or drying rate following the flood, and overall environmental conditions following the flood.

Soybeans are most susceptible to flood during the very early vegetative stage (V2—two trifoliate leaves fully emerged) and younger and the reproductive stages of R1 to R5 (flowering and pod set). Research suggests that varieties can differ in their tolerance to flooding. Another compounding factor is the amount of soil sediment left on the soybean plants and how long the sediment remained on the plants. The coating of sediment reduces the plants ability to photosynthesize and this reduces the ability of the plant to recover from the stress. Dr. Holshouser in his article reviews much of the research on yield loss so please refer to that article for more details. In general, it’s safe to say that estimating yield loss at or shortly after a flood is very difficult since to a great degree the environmental conditions for the rest of the growing season can have a great impact on the final yield loss.

Fungicides for Disease Control in Corn

Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu

Researchers across the country have rated commercially available fungicides for their efficacy on major foliar diseases of corn and compiled a table of this information. This resource is available as a pdf by clicking on the table below. In the future we will conduct experiments in Delaware that provide growers with additional information on how to effectively incorporate fungicides into their integrated pest management programs.

CDWGtable

Anthracnose and Root Rots in Corn

Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu

Anthracnose
Anthracnose was diagnosed on corn seedlings submitted to the University of Delaware diagnostic clinic. The fungus responsible for anthracnose, Colletotrichum graminicola, causes disease on leaves, stalks, and ears of corn, with the stalk phase being more important from a yield loss standpoint. Anthracnose is common early in the season in no-till or minimal tillage fields and is generally more severe in fields where continuous no-till corn has been grown.

Symptoms of anthracnose appear initially on lower leaves as small, oval, water-soaked spots that enlarge and turn tan to brown with yellow-brown borders. Lesions may coalesce and blight entire leaves. Older lesions will turn gray in the center with small black fungal structures. These fungal structures (acervuli) contain black spines (setae), which can be visualized in the field with a hand lens. Leaf lesions do not indicate that stalk rot will occur later in the season. Root infection by C. graminicola is more likely to cause stalk rot than foliar infections. Detection of foliar symptoms early in the season should alert scouts to keep an eye out for stalk and ear symptoms later in the season.

This fungus overwinters on residue where it grows and produces spores. Spores spread by wind or rain to leaves, where infection occurs. Severe leaf damage can result after long periods of heavy overcast and wet weather. Anthracnose management is based on the use of resistant hybrids, crop rotation, tillage, and balanced soil fertility. Fungicides that control foliar symptoms are not likely to result in a yield benefit and are not recommended in most cases.

cornanthracnoseCorn seedlings with symptoms of early season anthracnose.

Root Rot
Waterlogged soils result in nutrient and oxygen deficiencies, slowed germination, and reduced root growth, which contributes to infection by root rot pathogens. These pathogens include Pythium, Fusarium, and Rhizoctonia. Flooded conditions stress corn seedlings and allow pathogens to easily infect roots and cause root rots. Other factors, such as insect or nematode damage may facilitate infection by root rot pathogens.

cornrootrotCorn seedlings with symptoms of root rot.

Treated seed may not be as effective in situations where soils are waterlogged because fungicides are being asked to do more for a longer period of time. In serious cases replanting may be required, but often disease is limited to a few small areas within the field where drainage is poor. Plants with low levels of infection may be able to recover if environmental conditions favor plant growth.

Announcement
This summer I would like to help growers to scout fields for plant diseases. If anyone is interested please contact Nathan Kleczewski (phone: 302-300-6962; email: nkleczew@udel.edu).

Agronomic Crop Insects – June 28, 2013

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Alfalfa
Continue to sample for potato leafhoppers on a weekly basis. We are starting to see a significant increase in populations and a few fields with yellowing. Once plants are yellow, yield loss has already occurred. The treatment thresholds are 20 per 100 sweeps on alfalfa 3 inches or less in height, 50 per 100 sweeps in 4-6 inch tall alfalfa and 100 per 100 sweeps in 7-11 inch tall alfalfa.

Soybeans
We can find a variety of defoliators in soybean fields including grasshoppers, green cloverworm, oriental beetles and bean leaf beetles. Green cloverworm larvae are light green with three pairs of white stripes running the length of the body. In addition to the three pairs of legs near the head, they have three pairs of fleshy legs near the middle of the body, and one additional pair at the end of the body. Larvae wiggle vigorously when disturbed. Smaller larvae may drop from the leaf when disturbed. Young larvae skeletonize the underside of the leaf. Older larvae chew irregular shaped holes in the leaves and can eat all of the leaf except large veins. Although populations of green cloverworm generally increase in number from July through September, if the weather turns dry, we often see an earlier increase in numbers. Before bloom, the defoliation threshold in full season soybeans is 30% defoliation.

We can also find leafhopper populations in seedling stage soybeans. As a general guideline, a control may be needed for leafhoppers if you see plant damage and you find 4 leafhoppers per sweep in stressed fields and 8 per sweep in non-stressed fields.

Inking in Peaches and Nectarines

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Inking of peaches and nectarines is the appearance of dark colored, blue-black spots on fruit surfaces. While these spots are superficial, they cause the fruits to be unmarketable or be a second grade. Inking is due to damage to skin cells and the death of these cells but not the tissue below. Susceptibility varies with variety. Inking may appear when the fruit is on the tree but most often occurs after picking when abrasion occurs during harvest and handling.

Research in California has shown this disorder is caused by abrasion in combination with high concentration of certain metals such as aluminum, copper or iron. These metals may come from water or applied products such as fungicides, insecticides, or foliar fertilizers. For example, Imidan and Delegate insecticides have high levels of aluminum; the miticides Vendex, Acramite, and Omite have high levels of aluminum and some also have high levels of iron; the fungicide Elite has a high level of aluminum. Wash water high in iron or low in pH can increase inking problems

Another cause can be excess rain at harvest causing swelling and some cell damage along with associated storm damage and abrasion. This, in combination with metals, can increase the incidence of inking.

Control of inking includes reducing the amount of metals that go on fruit, reducing abrasion damage, and avoiding late applications of products that can increase inking (do not use during the 3 weeks before harvest).

Captan fungicide can also cause spotting, streaking, and bronzing on peaches if applied too near to harvest and at too high of concentrations. It has also been implicated in inking damage.

Spotted Wing Drosophila Detected

Joanne Whalen, Extension IPM Specialist;

We found our first adult spotted wing drosophila (SWD) flies in our traps in Kent and Sussex Counties this past week. Although there are no thresholds available based on trap catches, it does mean that small fruit growers will need to maintain a tight spray schedules for this very damaging insect pest. For more information on management of SWD in fruit, you will want to consider subscribing to Rutgers Plant Pest Advisory http://plant-pest-advisory.rutgers.edu/. You can also check the following link from Michigan State for additional information: http://www.ipm.msu.edu/invasive_species/spotted_wing_drosophila.

Reminder – you will need to check all pesticide labels for rates and restrictions as well as determine if they are labeled in your state.

Tomato Late Blight Reported in New Jersey

Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu

Late blight has been reported in a small organic tomato field in Mercer County, New Jersey. Indications are that this is an isolated case, but anyone growing potatoes or tomatoes should continue to scout their fields for late blight and apply preventative fungicides as needed. Additional information on late blight control can be found in the 2013 Commercial Vegetable Production Recommendations and recommended spray intervals can be found in this week’s potato disease advisory update.

Ozone Injury to Vegetable Crops

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

With the hot, humid weather, we are starting to see evidence of air pollution damage in sensitive vegetable plants.

Vegetables most susceptible to air pollution include potatoes, watermelons, cantaloupes, snap beans, pumpkins, and squash.

Damage is most common during hot, humid, hazy weather with little wind. Air inversions, when warm air at the surface is trapped by even hotter air in the atmosphere above, lead to build up of air pollutants that cannot disperse and, consequently, plant injury. The most common form of air pollution injury to plants is ozone damage. Ozone is a strong oxidant and is formed by the action of sunlight on products of fuel combustion. It is moved from areas of high concentration (cities, heavy traffic areas) to nearby fields.

Ozone injury in susceptible vegetable varieties develops when ozone levels are over 80 ppb for four or five consecutive hours, or 70 ppb for a day or two when vegetable foliage at a susceptible stage of growth. Because it occurs in areas with high levels of automobile exhausts, crop injury is often visible on fields in close proximity to roads, especially with heavy summer weekend traffic. High pollution indexes in Baltimore and Washington are also a good indication that ozone damage may occur.

In potatoes, symptoms of ozone damage occur on the most recently emerged leaves and can be seen as a black flecking. Early red varieties are most susceptible.

Injury on watermelon leaves consists of premature chlorosis (yellowing) on older leaves. Leaves subsequently develop brown or black spots with white patches. Watermelons are generally more susceptible than other cucurbits to ozone damage. Damage is more prevalent when fruits are maturing or when plants are under stress. Injury is seen on crown leaves first and then progresses outward. Seedless watermelon varieties tend to be more resistant to air pollution injury than seeded varieties, so injury often shows up on the pollenizer plants first. “ice box” types are the most susceptible.

In muskmelons and other melons, the upper surface of leaves goes directly from yellow to a bleached white appearance.

Ozone injury on squash is intermediate between watermelon and cantaloupe starting with yellowing of older interior or crown leaves. These leaves subsequently turn a bleached white color with veins often remaining green.

In snap and lima beans, ozone causes small bleached spots, giving a bronze appearance on upper leaf surfaces and pods. Leaves may ultimately turn chlorotic and senesce (drop).

Ozone injury can be easily misdiagnosed as mite injury, pesticide phytotoxicity, or deficiencies.

The key to avoiding air pollution injury is to plant varieties that are of low susceptibility and to limit plant stresses. Certain fungicides such as thiophanate methyl (Topsin and others) offer some protection against ozone damage.

 ozonewatermelonOzone injury on watermelon

ozonesquashOzone injury in summer squash