Crop, Disease & Insect Update Fulton Co

Soybeans have improve in appearance and yield outlook over the past month. The dry weather has allowed the plants to root down, nodulation to provide nitrogen and some of the damaged plants to recover. During my August 6&7 trip through the county, the bean stage of growth ranged from R1 to R6 with 84% of the beans in R4-R6 stage. R4 is the full pod stage where a 3/4 inch pod is on one of the four upper nodes. R6 is full seed where a pod containing a green seed fills the cavity at one of the four upper nodes.
Soybean Insects-From and insect standpoint Japanese beetle are the most prevalent insect, some bean leaf beetle were found and a few grasshopper. For these defoliating insect plants in R4-R5 can tolerate 15% defoliation and R6-R8 (Maturity) 25% defoliation when looking at the entire plant.
Soybean Aphid were found in 6 of 44 fields but at very low levels of less than 1 per plant on average. The highest single plant counts were 10 aphids per plant. Fields that had aphids also had Asian Lady Beetles active on plants with higher populations. The threshold for insecticide treatment is still 250 aphids per plant plus with the advancing growth stage most field will not require treatment. Instead what we are seeing is the normal off year build up of populations in the fall. Monitoring fields in flowering stages or double crop would be suggested. Another scouting focus would be field that were treated with insecticides during the week of July 28th. Fields treated this week would have had beneficial insects killed which may allow for the rapid build up of Soybean Aphid is those fields depending on the residual length of the insecticide used and the growth stage of the plants.
Disease is generally limited to brown spot on the lower leaves but some downy mildew is beginning.

Corn has all progressed into the reproductive stages. Some corn is still pollinating and is in the blister stage. A majority of the corn is the R3 or milk stage which is very comparable to what we eat as sweet corn in appearance. A few fields show aborted or unpollinated kernels and ear tips not filled to the end. Diseases are still generally very low. The 2008-25 issue of C.O.R.N. has two articles worth looking at Assessing the Success of Pollination in Corn and Evidence of Drought and Heat Stress Appearing in Corn Fields You can now find grayleaf spot and rust is still present but has generally not spread very far. Insects are low as well a few corn rootworm beetles and some evidence of European Corn Borer can be seen.

Wheat while 2008 crop is in the books 2009 planning has already begun. The 2008 Wheat Performance Trial Information is available on line and an article on Wheat Fungicide Seed Treatment can be found in the C.O.R.N. newsletter 2008-25 edition. If you are planning to use your own seed please take a close look at this for recommendation for wheat scab and glume blotch (Stagonospora nodorum) control since both were seen in the area with the 2008 crop.

Does the level of Corn Disease justify spraying?

The answer here is no, unless you are working with a susceptible hybrid or variety and the disease is present. The most damaging diseases for Ohio would be Gray Leaf Spot and Northern Corn Leaf Blight. This year does seem to be providing the proper environment for rust and we are seeing high levels reported on popcorn and sweet corn which have low resistance to rust. Most all of the field corn have a good rust resistance built in. Information on corn rust can be found in the factsheet AC 0031-01 Common Corn Rust found below. All other scouting results have shown other common diseases to be at very low levels.

So why spray corn with fungicides? Bob Nielson, Purdue University Corn Agronomist has put together a compilation of some articles on this topic from around the country in an article entitled "Corn Fungicide Hoopla 2008". Dr Nielson provides the definition of hoopla and then links to several articles addressing the third party suggestions and evaluations of the practice.
If you want to get right to the yield data the best summary of midwestern data is assembled by the University of Illinois Making Profitable Fungicide Applications in Corn.

Common Corn Rust

AC-0031-01

Common corn rust rarely causes significant yield losses in Ohio field (dent) corn. However, occasionally field corn has been damaged when environmental conditions favor the development and spread of the disease. Sweet corn is generally more susceptible than field corn. Common rust can usually be found in corn fields sometime during the growing season, but generally does not appear before tasseling. In those years with exceptionally cool summers, and especially on late-planted fields or sweet corn, yield losses may be expected when the leaves above the ears become severely diseased.

Symptoms

Common rust of corn can be easily recognized by the development of dark, reddish-brown pustules scattered over both the upper and lower surface of the corn leaves. Pustules appear oval to elongate in shape, are generally small, less than 1/4 inch long, and are surrounded by the leaf epidermal layer, which appears as a whitish covering. These pustules may appear on any above ground portion of the plant, but are most abundant on the leaves.

Causal Fungus

Puccinia sorghi is the fungus causing common rust in corn. The reddish-brown color of the pustule is actually the coloration of the repeating spore or uredospores. These spores are produced throughout the summer and infect new leaf tissue and are responsible for the spread of the disease. As the corn plant matures the pustules turn a brownish-black color due to the development of the darker pigmented spores or teliospores. In tropical regions teliospores infect the rust's alternate host, wood sorrel (Oxalis species). In temperate areas, including the U.S. cornbelt, the fungus does not infect wood sorrel and the teliospores have no real function.

Disease Cycle

The rust fungus overwinters as uredospores on corn or as other spore forms on wood sorrel in subtropical and tropical regions. Spores capable of infecting corn are blown northward during the growing season and become established on the corn crop. Rust development and spread is favored by prolonged cool temperatures ranging from 60° to 74°F and high relative humidity. When these protracted cool, humid conditions exist, susceptible corn hybrids and sweet corn varieties can become seriously affected.

Control

Although rust is frequently seen on corn in Ohio, very rarely has there been need for control on field corn. In field corn, highly resistant hybrids are available and most hybrids possess some degree of resistance. Pop and sweet corn can be quite susceptible. In seasons where considerable rust is present on the lower leaves prior to silking and the weather forecast is for unseasonably cool, wet weather, chemical control may be necessary. Fungicides are available for rust control. Consult label recommendations for rates and application timing. Early application is necessary for effective disease control.

Crop Progress Pest Report as of 7/11/08-Fulton County

Thursday and Friday afternoon last week I traveled the route of Road B and Road L between to Lucas and Williams County lines. I visited the same 35 Corn, 42 Soybean and 25 wheat fields that have been on the route. I was unable to get to a couple fields due to an accident investigation nearby.

Corn has progressed to the early pollination stages. In fact 12 (34%) of the fields were in the R1 stage (silking) , 9 (25%) fields were in VT (tassel) and 14 (40%) fields were in late vegetative (V10-V15). The crop generally looks good but there are water damage areas. Insect pressure is low with some European Corn Borer that had entered the stalk (4 of 35) and very limited numbers of Corn Rootworm beetles (2 of 35). It maybe just a little bit early to evaluate rootworm numbers but we after historically high numbers in 2007 it was noteworthy that very few were found. From a disease standpoint the only disease noted was leaf rust and it was generally just a pustule or two on a leaf and extremely limited in intensity.

Soybeans have generally taken this wet weather harder than the corn. Much of the worst loss of crop was east of 13. One 80 acre field was around 50% lost to flooding from July 2 and 3 rains. From a growth stage standpoint there were 5 (12%) fields in the R1 (beginning bloom), 34 (81%) in R2 (full bloom) and 3 (7%) in R3 (beginning pod). Digging up plants you were starting to see significant regrowth of the roots and some new nodulation. A few leaf feeding insects were present Japanese beetle and been leaf beetle could be found. From a disease standpoint brown spot was the most common disease with some phytopthora in a couple fields. More information on scouting for soybean disease can be found at http://ohioline.osu.edu/b827/0003.html

Wheat was harvested in all 28 wheat fields I had been following. There were still a couple wheat fields not harvested in between stops but we were approaching completion. Wheat yield reports appear to be in the 70-95 range with more it seems in the mid 70-80 range. It seems that 75% of the field were or will have the straw removed. From a nutrient standpoint a ton of straw contains 11 pounds of N, 3 pound of P2O5 and 15 pounds of K2O which at today's fertilizer prices are about $20 a ton plus the value of the organic matter. A general straw yield is 2.7 tons per acre.

Wheat Harvest Between Rainfall

Wheat harvest began in Defiance County over the Independence Day weekend. A few well-drained fields were dry enought to support harvest equipment whereas, wetter fields wait for improved field conditions and for the crop to rippen. Early report provide good yields in the range of 70-85 bushel per acre with excellent test weight. Grain moisture is reported in the range of 14-16% with a few growers harvesting wheat a bit sooner than normal to plant double crop soybeans.

Forage harvest continues to be a challenge with the recent rainfall. Alfalfa producers should scout for potato leaf hoppers during the regrowth period following 1st cutting.

Soybean plants that remain in saturated soils are beginning to show phytophthora stem rot. Classic sympotoms are plants, scattered throughout the wet areas with the chocolate brown canker moving up the plant. The upper part of the plant will turn yellow and wilt.

Corn has entered a period of rapid growth and will soon be determining the number of kernals per row on the ear. This is usually complete about one week before silking (R1) or about the V17 stage.

July 2-3 Rains bring flooding concerns

Today's rainfall report are astonishing. It appears the heaviest rainfall was north of the turnpike. Rainfall in the Wauseon area was 2.5 inches but north of the turnpike reports of 5-7.5 inches are common across much of northern Fulton County. Below are articles reprint from 2003 edition of CORN newsletter on flooding in corn and 2006 CORN related to soybean and flooding injury.

Early Season Ponding and Flooding Injury to Corn-Dr Peter Thomison

Recent heavy rains have generated questions about flooding and ponding injury in corn. The following are some tips to consider when evaluating possible damage from water saturated soil conditions.

The extent to which flooding injures corn is determined by several factors including: (1) plant stage of development when flooding occurs, (2) duration of flooding and (3) air/soil temperatures. Prior to the 6-leaf collar stage (as measured by visible leaf collars) or when the growing point is at or below the soil surface, corn can usually survive only 2 to 4 days of flooded conditions. The oxygen supply in the soil is depleted after about 48 hours in a flooded soil. Without oxygen, the plant cannot perform critical life sustaining functions; e.g. nutrient and water uptake is impaired, root growth is inhibited, etc. If temperatures are warm during flooding (greater than 77 degrees F) plants may not survive 24-hours. Cooler temperatures prolong survival. Once the growing point is above the water level the likelihood for survival improves greatly.

Even if flooding doesn't kill plants outright, it may have a long term negative impact on crop performance. Excess moisture during the early vegetative stages retards corn root development. As a result, plants may be subject to greater injury during a dry summer because root systems are not sufficiently developed to access available subsoil water. Flooding and ponding can also result in losses of nitrogen through denitrification and leaching.

If flooding in corn lasts less than 48 hours, crop injury should be limited. To confirm plant survival, check the color of the growing point. It should be white to cream colored, while a darkening and/or softening usually precedes plant death. Also look for new leaf growth 3 to 5 days after water drains from the field. Sometimes the growing point is killed by bacterial infections during and after flooding, but plant growth continues in the form of non-productive tillers (suckers).

Disease problems that become greater risks due to flooding and cool temperatures include pythium, corn smut, and crazy top. Despite fungicide seed treatments, pythium root rot contributed to serious stand reductions in many corn fields last year. The fungus that causes crazy top depends on saturated soil conditions to infect corn seedlings. There is limited hybrid resistance to these diseases and predicting damage from corn smut and crazy top is difficult until later in the growing season.

Flooding Injury to Soybeans - Anne Dorrance

Several past studies have evaluated the effects flooding on soybeans. Research projects led by Dr. Tara Van Toai of the USDA-ARS and Department of Horticulture and Crop Science. In one study, soybean plants at the V2 and V3 stages were flooded naturally due to excessive rainfall, something we are all familiar with. Two 9-m wide transects across the flooded area within each field were divided into plots of 9 m by 9 m according to flooding duration: no flooding, 1 to 3 d, 4 to 6 d, and 6 to 8 d. Yield was reduced primarily due to reduced plant populations, shorter plants and fewer pods developing per plant. Other studies showed yield losses of 20% when soybean fields were flooded for greater than 2 days, but it should be noted they still had a yield. Some varieties can tolerate flooding more than others. For those fields with greater than two days of total saturation, ponding, can expect to see some long term effects. Secondary factors, such as root rots, will also contribute to the damage. Growers should note the varieties and compared varieties that were flooded for the same length of time. Some varieties will be impacted to a greater degree than others.

Head Scab Present but Low Counts

On June 24 & 25, twelve fields across Fulton County were scouted for head scab. Head Scab causes part of or all of an individual head to be bleached out on close observation you may see a orangish-pink growth where the kernel is attached and the lower glume. Every field had some scabby heads in them. The average was 5.6% of the head affected. The range was 1-15%. Counts were made per foot of row. The average head count per foot of row was 38 heads. The head count compares with previous years 2006-38.8 and 2005-39.



Two fields had noticeable levels of Glume blotch which is a black coloration of the glumes that surround the kernel. This particular disease can impair grain fill and result in lower test weights.

Fulton County Crop Scouting Update 6/23/08

During the past week I have done a crop scouting transect across Fulton County using County Road L and County Road B from the Lucas to the Williams County line. At each stop within a mile I noted crop growth stage, row width and plant population. Plus noted any weed, disease or insect presence. This is a summary of those observation.

The Corn crop has really taken off. The average growth stage would be V6 with a range of V3 to V9. Not surprisingly the crop is all planted in 30 inch rows the average plant population was 29,750 plants per acre. The range was 24,000 to 36,000. I did observe 1st generation corn borers at low levels in 3 fields of 37 fields scouted.

The Soybean crop is starting to work through the yellow stage from V1 to V2 where the seed nitrogen has run out and the nodules are fully fixing nitrogen. The average growth stage is V3 with a range of V1 to V6. Population and row widths are noted in the table below. The biggest pest problem is weeds which if they have not been taken care of should be a top priority. Lambsquarter, ragweeds and others are growing well in addition to the soybeans. Some Bean Leaf Beetle activity was noted but a very low levels. From a disease standpoint typical brown spot is seen but nothing that would be economical to treat.

Wheat continues to mature. A big change in color can be seen in the last week. Armyworm was being found in low numbers 1-3 per linear foot of row. Most wheat is at the point where all we need is a couple more weeks and we will be in harvest. Typically we start around July 10 and this seems to be our time frame at this point. Any high temps from this date on will hasten drydown. Harvest of wheat can begin as moisture reaches 18-22%. If you plan to double crop soybeans harvesting at higher moisture and running air on the wheat in the bin to finish drying to 13% can provide a couple day earlier planting date for double crop beans. Planting double crop beans after July 10 becomes increasingly less profitable and is why it is not a common practice here in NW Ohio. But has been successful if we have moisture about 1 out of 5 years. With soybean prices trading above $14.50 some will consider it. The current longterm weather forecast is somewhat favorable with the one month forecast of below average temperatures and above normal rainfall and the three month forecast of normal rainfall and temperatures .

More information on double cropping soybeans can be found at the link highlighted in the previous text.

What to Do with Thin Soybean Stands

Most corn and soybean fields in the local area have gotten off to a good start. There are some soybean fields that are the exception and a decision on what to do with these fields will need to be made soon.

The thought process on replanting is sometime straight forward where large areas have not emerged. Several of the field I have seen are not quite as straight forward. The stands are thin or rows are missing but there are some beans there. Likely we are seeing the effects of some of the germination problems that were associated with some lots of seeds and difference in some cases of planting depth from row to row.

The first question to answer is, Is this a fairly even stand. If the stand is even then it is worth doing a stand count and if the population is 75,000-90,000 plants per then the potential of 90% is doable. This stand may require an extra herbicide pass to keep weeds under control, but this type of stand may at this point be best left alone.

If the stand is fairly uneven then a closer evaluation is required. A publication on soybean replanting from Iowa State does a good job of summarizing the stand evaluation process and I would highly recommend taking at look at it. Soybean Replant Decisions.

5/30 Crop Report for Fulton County

Corn planting is completed. Emergence is progressing well and stands are good. Some nitrogen sidedressing is under way. Several have asked about nitrogen rates recommended by OSU. Midwest universities have moved away from a crop response model for N rates and have adopted an economic model that takes into account the current price of nitrogen and corn. The rates suggested are based on crop response models but acknowledge the wide range in corn yield response to various nitrogen rates. The model uses an Excel Spreadsheet format and can be found at Nitrogen Spreadsheet. For example with a corn price of $5.60 and anhydrous price of $900 a ton ($0.55 per pound of N) a total of 149 to 158 pound of N is recommended.

Soybeans are 65-75% planted. Emergence of the earliest planted beans began this week.

Wheat is in the 10.1 (head emergence) and will soon be in the 10.5 stage (flowering). This is the time to monitor for the potential for head scab. The wheat scab predictor website is an excellent monitor of weather conditions by region. Remember, scab develops best when wet, humid conditions occur during the seven days before flowering, so even if it is dry at flowering, any three to six days of extended rainfall during the seven days before flowering would be enough to increase the risk of scab. Now that we have fungicides labeled for head scab suppression, the risk tool would be of great value to help guide fungicide application decisions. Proper timing of fungicide application is critical for head scab suppression. It is extremely important to apply the fungicide at anthesis (when fresh male floral parts are seen sticking out of the heads), well before visual symptoms are seen on the heads. Symptoms usually develop about three weeks after anthesis (depending on the weather), so the risk tool can be used as a predictor of the risk of scab occurring to help guide fungicide decisions. In general, fungicides provide about 45 to 55% reduction in scab and vomitoxin, if applied at anthesis. Applications made 3 days before or 3 days after anthesis will reduce the level of suppression.

Alfalfa harvest has continued this week and should eliminate the potential for alfalfa weevil damage. Only a few fields have had the presence of this insect and damage has been fairly limited.

Defiance County 5/28 Crop Progess

Corn planting is essentially complete with approximately 30-40% emerged. Some concerns about sidewall compaction as the soil continues to dry. Soil crusting after planting has been noted on some tilled ground which may make emergence difficult. Rain showers are forecasted for Thursday night and Friday that could improve emergence.
Soybeans are 50-60% planted with approximately 10% emerged. Soybean seed supply remains tight. Current conditions and weather forecast suggests not a lot of widespread replant for 2008.
Alfalfa first cutting has begun with the remaining to be cut over the next 1-2 weeks. Some fields were sprayed for alfalfa weevil last week as larvea counts were greater than 2 per stem, defoliation greater then 50%, and harvest more than 2 weeks away. Approximately 25-30% of the alfalfa acres were damaged or distroyed by winter injury. Many of those fields have been killed with herbicide and planted to corn.

Garlic? Onion? Star of Bethlehem...

A plant was recently brought in as a weed in a corn/soybean rotation that caused me to spend a few minutes going through possibilities and then deciding I had something different. At first it looked like onion, but the bulbs did not have an onion odor, maybe wild garlic but no garlic odor, it really had no odor at all. I then noticed a distinct white mid-vein. The flower bud was there but not yet open could only tell that the plant had a white flower. A few minutes on the web and I had identified Star-of-Bethlehem. Not an common weed in a corn/soybean rotation that is in fact an escaped horticultural plant found in northern US and Canada. As you can see from the field view picture, the plants can be very thick in the field and one can image planting difficulties plus the potential moisture loss. The bulbs range from very small up to about quarter size. When in flowering you can note the 6 petal, white flower. The plant primarily spread by the bulbs so field to field spread is from tillage. Research from Southern Illinois University showed the best 12 month control came from Gramoxone application in the spring. SIU Factsheet on Star-of-Bethlehem.

5/21/08 Crop Observations for Fulton County

Wheat is generally between Feekes growth stage 9.0 and 10.0. Growth stage 9 is where the collar region of the flag leaf has cleared the end of the stem and Growth stage 10 would commonly be referred to as the boot stage where the head is still inside the stem but close to emergence. Generally few diseases are noted with only certain susceptible varieties with significant powdery mildew observations. No significant reports of wheat insects- aphids or armyworm have been received. Reports of injury from fall 2,4-D applications have been recieved from Fulton County. See previous article for more details or the CORN Newsletter.

Corn planting has progressed somewhat and we are nearing 60-70% planted which could fairly quickly change with a few more sunny days. The earlier planted crop is emerging. Stands appear to be very good, even in wet spots and emergence is not being delayed within the row. As expected with the cold days and nights the emerged plants are yellow with some of the common purple edges.

Soybean planting is generally just off to a good start. Maybe 15-20% have been planted with the first emergence just beginning.

Alfalfa is fairly advanced in growth and the first cutting was seen on May 20. Some alfalfa weevil activity has been noted but seems to be more scattered than reports just to the south of us. The weevil that have been found are also very small so more damage could potetnially be seen if harvest is delayed.

2,4-D Herbicide Injury to Wheat

Wheat fields that received an application of 2,4-D herbicide last fall are showing injury sympoms. The damage found ranges from 10% up to 90%+. The injury appears as distorted stems, crinkled leaves and stunted plants. Difference have been noted by variety, planting date and stage of tillering last fall. Observations and labels information have been summarized by Dr Mark Loux, OSU Extension Agronomist in the May 19th CORN Newsletter from OSU Extension. "Many of the fields that were most severely affected were treated with a combination of Peak and 2,4-D last fall, and the use of 2,4-D in these treatments may be a primary cause of the injury. Peak is labeled for postemergence application to wheat in fall or spring, from emergence until the second node is detectable in stem elongation (Feeke’s Growth Stage 7). Labels for 2,4-D products vary in their wording on the use of 2,4-D in wheat. The more conservative labels state that 2,4-D should be applied in the spring after wheat has fully tillered, while others (including some products used in the affected fields) state that application can be made after tiller initiation with no mention of fall versus spring application."

Options maybe limited for the most severely affected fields. 1) The Peak label has a 10 month recrop restriction for soybeans. pH above 7.8 also play into decisions about replanting. Refer to product label for details. A bioassay maybe used and is outlined in the previously mentioned CORN Newsletter article. 2) Field could possibly be harvested as wheatlage then replanted to corn. Restrictions on forage use should be checked. 3) Field could be sprayed with roundup and planted to corn. These fields would then need to be scouted for armyworm development.

For more details see the Crop Observation and Recommendation Newsletter-CORN.

Defiance County 5/14/08 Progress Report

Alfalfa grow is progressing rapidly with typical stem heights of 10-16 inches of growth. Growers should be scouting for alfalfa weevil. On 5/9/08 I visited three (3) alfalfa fields and observed noticiable tip feeding on about 20-30% of the stems. Further inspections revealed small (1/8-1/4 inch) alfalfa weevel larvae tucked in the cluster of new leaves and leaf petioles. Levels were below economic threshold but will require rescouting by 5/16/08. (Economic threshold)

Corn is about 40-50% planted with some early corn emerged. Rain delays may force the question of switching to shorter hybrids but full-season hybrids should still be considered until early June.

Wheat development is at Feekes stages 8-9. Growers should scout for foliar diseases on suceptable varieties first and determine the presence and severity. (Ohio Wheat Diseases)

Fulton County 5/12/08 Progress Update

Wheat has entered the Feekes 7.0-9.0 stage. These stages are past the point where most herbicide applications are labeled. Application can result in sterile heads so carefully look at stage before making any further herbicide applications. Report and scouting I have done have identified very little wheat disease. Stagnospora was found in one field. I have not found powdery mildew but it likely exist at very low levels. No insect problems are being identified but we will continue to look for armyworm.

Corn planting did progress in the county to where we appear to be around 50-60 percent complete. Some are reporting being done while others are just getting started. The earliest planted corn has emerged and stands are good.

Soybeans are just started with around 10% planted.

Planting between the rain showers

Planting has progressed primarily focused on getting corn out. Friday morning was very active as I drove through the western half of the county with tractors rolling and dust flying. I have reports of some farms with all nearly all of the corn planted and others that just have a field or two in. Most of the farms nearly complete are in the eastern half of the county where sandier soils allow for an earlier start. Some farmers are planting around the wet spots in hope to come back later and fill in.

Wheat nitrogen topdressing was finally finished up last week. The wheat has generally hit growth stage 6 and thus need to be careful with applications particularly herbicides due to potential injury. The canopy is closing in and the crop will advance quickly so scouting for disease particularly where the variety is susceptible to powdery mildew or stagonospora.

Since April 20th we have received 117 GDD. Rainfall for the week of April 28th inculed .30 inches Monday and 1.3 inches Saturday. The low temperature of 28 degree made for a cold morning but should have had limited effect except for the most tender of vegetation.

Fulton County planting progress is slow

A slow start to planting due wet cool soils. Average soil temperatures reported at OARDC Northwest Agricultural Research Station are 56 degrees over the past week. Soils are starting to dryout with sunshine and winds helping but persistent wet spots are making most fields unsuitable for much heavy equipment. Most activities in the past week have been preplant fertilizer applications, hauling manure and preparing for planting.

Wheat is near Feekes growth stage 5. Good progress has been made on wheat topdressing.