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 IN THIS ISSUE...  July 2003

Consider Alternatives to Late-Planted/Replanted Corn
Not all of the corn crop is in the ground in Ohio, and unfavorable weather conditions may drive growers to plant an alternative crop in place of the small percentage of unplanted or replanted corn throughout the state.

Peter Thomison, an Ohio State University Extension agronomist, said that corn can be planted as late as mid-June, although growers will be looking at significant yield reductions.

"I would like to have seen all of our corn planted by the first week of June at the very latest. We can probably plant as late as mid-June because the corn can adjust to later planting dates, but we are looking at a significant yield drop," said Thomison. "For corn planted after June 1, we are looking at a crop that'll probably do no better than 100 bushels per acre. In southern Ohio, at least for silage purposes, growers can plant in late June and get a forage crop out of it."

According to the Ohio Agricultural Statistics Service, 97 percent of the corn has been planted with 96 percent of it emerged. But with recent persistent rains and cool to mid temperatures, only a little over half of the crop is rated in good to excellent condition. Over 70 percent of the topsoil is saturated.

Thomison said that corn planted in April is established and growing well, while much of the corn planted the beginning of May is struggling in marginal fields plagued with saturated conditions and root diseases. Growers who have not yet planted or are facing replanting due to field conditions may be considering other crop alternatives.

"If growers haven't used corn herbicides and are in a good crop rotation system, soybeans is one crop that growers can consider," said Thomison. "The major reason growers lean towards soybeans is because there is a market to sell it and growers are familiar with the crop."

Another crop that also shows promise as a replacement for corn is grain sorghum.

"The potential use of grain sorghum always comes to the surface in years where we have late planting," said Thomison. "It's a good crop. It's drought resistant, and has a better root system, tolerates stresses and grows better on marginal soils than corn."

Despite its good virtues, the crop does have its drawbacks. Ohio lacks a market for growers to sell their crop and with lack of short season hybrids available that are compatible with eastern Corn Belt conditions, growers would be scrambling to find seed and manage an unfamiliar crop during a crisis situation.

"If growers have never handled grain sorghum before, we would not recommend they try a new crop under emergency conditions," said Thomison.

Growers interested in grain sorghum as an alternative crop can consult Purdue University's grain sorghum production Web site at http://www.agry.purdue.edu/ext/sorghum/index.html. Bulletin AY-312-W "Delayed Planting and Hybrid Maturity Decisions" at http://ohioline.osu.edu.

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Yield Expectations for Late Corn Plantings
Most farmers who are still planting corn have switched to early maturing hybrids (95-103 day relative maturity). Based on past OSU research, such corn planted in mid-June will likely yield about half the expected yield of a full season crop planted May 1. Good rainfall during the remainder of the growing season and mid fall (late killing frosts) could reduce such losses. However, as we saw in 2002, drought during July and August could destroy a late planted crop. Late planted corn is typically associated with higher grain moisture at harvest, lower test weights, and greater potential for stalk lodging problems.

We compared planting date effects on hybrids representing a range of maturities several years ago in a study conducted at Hoytville in northern Ohio. Although adapted hybrids (106-115 days) produced significantly greater yields than the short season 97-day hybrid planted before mid-late May, the 97-day hybrid produced yields similar to the fuller season hybrids for the mid-June planting dates. Moreover, the 97-day hybrid reached harvest moisture (25% moisture) 12 days before the earliest adapted hybrid. Results of this study suggest that acceptable yields can be obtained with corn planted as late as mid-June when growing conditions are favorable, but they don't indicate the potential yield reduction that might occur under heat and drought stress.
-Corn #2003-18

Current Weed Control Issues
1. In fields that have had no weed control yet this spring, most perennial broadleaf weed species and many perennial grass species are currently in the bud to early flower stage. This stage is excellent for long-term control when using glyphosate. To control Canada thistle and quackgrass use at least 0.94 pound acid equivalent (lb ae)/A of glyphosate (28 ounces/A of Roundup WeatherMax or 40 ounces/A of 3.0 lb ae/gallon glyphosate formulations). For most other perennial broadleaf weeds use at least 1.5 lb ae/A of glyphosate (44 ounces/A of Roundup WeatherMax or 64 ounces/A of 3.0 lb ae/gallon glyphosate formulations). If horsenettle, groundcherry species, common and honeyvine milkweed, and a few others are present, consider rates higher than 1.5 lb ae/A.

2. The delay in planting due to the wet weather in SW Ohio, especially where the glyphosate-resistant marestail (horseweed) exists has created extremely large marestail plants (>2.5 feet tall). In these fields, the best way to control the large marestail is to use two passes of tillage. The next best option is to consider 1.5 lb ae/A of glyphosate or greater and add Classic at 0.75 to 1.0 ounce/A or FirstRate at 0.45 ounce/A before planting. Another option, if you have a good crop insurance plan, is to consider not planting these fields and work them when you get a chance. To ensure good coverage of weeds, consider 20 to 25 gallons/A of spray volume.
3. To control large (> 2 feet in height) annual weeds where no prior weed control has been done, apply at least 1.5 lb ae/A of glyphosate before planting. To ensure good coverage of the weeds, consider 20 to 25 gallons/A of spray volume. Using 10 to 15 gallons/A may not allow for adequate plant coverage for good control.

4. For Roundup Ready soybean fields with no residual herbicides applied and they were planted before May 20, the weeds will grow rapidly with these hot temperatures. Make sure you are applying the appropriate glyphosate rate for the weed size and species that are in the fields. The higher the glyphosate rate used, the less likely weeds are to become glyphosate-resistant.
 

5. In corn fields that still need a postemergence application, check the corn stage before applying herbicides. The hot temperatures this week will cause corn to be more susceptible to dicamba injury. Once corn is greater than 8 inches tall, it can be injured by dicamba. Using the lowest rate possible, drop nozzles, and a surfactant when mixed with other herbicides will help in reducing corn injury from dicamba. Once corn reaches the V6 stage (6 collars), no ALS-inhibiting herbicide should be applied broadcast over the top of corn as significant yield reduction may occur due to the pinched-ear syndrome.

6. Carefully scout any soybean field that had marestail present at the time of the burndown application. Due to the cool and wet weather, marestail continued to germinate until the end of May. Many of these plants are beginning to bolt, so control should be very easy at this time. Use glysposate at 0.75 lb ae/A on Roundup Ready soybeans, Synchrony STS at 0.5 ounce/A on STS soybeans and add additional Classic to get to 0.75 ounce/A of total Classic, adding MSO and a nitrogen source to the mix, or FirstRate at 
0.3 ounce/A on normal soybeans to control these small marestail.

7. According to the atrazine label, fields with applications of atrazine after June 10 should not be rotated to soybeans.

-Corn 2003 #19

New Pest Bugs Soybean Growers
Along with the stresses of weather, soybean growers might be faced with yet another problem: soybean aphids. The pest was recently identified in a Wooster field and entomologists are encouraging growers to scout their fields.

Soybean aphids are relatively new to the United States and to Ohio State University researchers. The pests were first identified in 2000 and were a major problem in northern Ohio and surrounding states in 2001, said Ron Hammond, an entomologist with the Ohio Agricultural Research and Development Center. Last year researchers were prepared to battle the bug, but it was almost non-existent.

"Two years ago, we didn't really realize we had the pest until too late," Hammond said. "And last year, it didn't really show up–it was low throughout the Midwest. We don't really know what it will do this year, but we hope it's like last year."

Based on the soybean aphid damage seen in 2001, Minnesota was expecting to spray over two million acres last year. Ohio was prepared to spray one-half million acres, and that was based on the damage seen only in the northern part of Ohio, Hammond said. If the aphids get into bigger soybean regions, it could be a major problem.

A population of soybean aphids can easily reduce yields by five to 10 bushels per acre, Hammond said. Injury from soybean aphids include pod abortion, and later in the season, small seed development.

If the soybean aphid becomes a problem, farmers would be facing $10 to $15 per acre of additional costs for spray, Hammond said. However, because it only takes three or four bushels to cover spray cost, the cost of spray is well justified compared to the losses caused by soybean aphids.

"I hope it's a problem we don't have to get into," Hammond said. "Growers have enough to handle with the weather and prices. They don't need to have another problem."

The pests, which cover the plant and suck the juices out of it, can get into the thousands per plant, Hammond said. Growers want to keep numbers minimal, but do not want to spray too soon or it will allow for the aphids to return by the end of the season. It is recommended to wait to spray until early- to mid-July when the plants are flowering and setting pods, and the majority of plants are covered with 250 or more aphids.

Soybean aphids, which are often mistaken for small potato leafhopper nymphs, overwinter on buck-horn. This host is usually found along hedges, fence lines, and wooded areas. But the Wooster field where the aphids were identified is not close to hedges, fence lines or woods, Hammond said.

The aphid also is thought to be a cool-season pest because of its invasion of northern United States, but researchers are not yet sure. If the aphids are a problem this year, more traits will be figured out.

"Every year we are learning as much as everyone else," Hammond said. "We have no exact answers for questions."

"We're worried about this pest because it's our job. Finding answers means fewer problems for farmers," he said.

While the soybean aphid means additional worries for growers, entomologists are intrigued. A lot of the aphids found in Wooster were heavily parasitized, Hammond said. That was not the case in 2001.

Parasites are a form of biological control and while they may not completely rid Ohio of soybean aphids, they could help. Hammond's colleagues from neighboring universities have been to China and Japan, where the aphid originated, looking for exotic parasites to combat the aphid.

"There is a lot of effort being put toward biological control," Hammond said. "Importing exotic parasites with more specific instincts could help control soybean aphids all of the time. It may be the answer."

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...Begin Testing, Inventorying Forages Now
Typically, hay can provide the majority of the nutritional needs of a cow herd during the fall and winter months. It's become apparent this year will be an exception. Already facing minimum Ohio hay inventory coming out of winter, the weather has allowed very little quality hay to be made this spring.

Certainly, taking an inventory of both the quantity and quality of your forages can't begin too soon. This will allow plenty of time to plan the most cost effective method for supplementing whatever forage has been harvested with the correct supplements.

To properly supplement livestock, each forage lot to be fed should be sampled and analyzed. The tonnage, the location in the hay storage area of each, also need to be recorded. OSU Extension forage testing fact sheet ANR-2-98, available on the web http://ohioline.osu.edu/anr-fact/0002html and at OSU Extension offices, describes the proper sampling techniques for various forages and explains how to most effectively utilize the results.

Many local OSU Extension offices, and also feed suppliers, have a forage test probe that can be borrowed for securing the sample. Your local OSU Agriculture Extension Agent as well as your feed supplier can also provide a list of laboratories that provide forage testing services.

Another advantage to keeping detailed records of both forage quantity and quality is for crop disaster and/or crop insurance purposes. Obviously there are no guarantees that a Forage Quality Loss Program will be forthcoming from FSA, however, it wouldn't surprise many if one became available again throughout Ohio in 2003. In fact, there has been one in Ohio each of the past three years. Consider contacting your local FSA and discussing forage loss programs, and the alternatives for having forage quantity and quality measured in the event we see another similar program this year.

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Coping With Summer Algae Problems! 
Here we are into early summer and filamentous algae problems are center-stage once again. Indeed, this past spring was the worst I've ever seen for the algae–which undoubtedly will make our summer problems that much worse. Why did filamentous algae become so problematic so early this year? Well, it's difficult to be certain but I suspect the mild winter and that very warm week in early April are to blame. They combined to allow filamentous algae to gain the upper hand early on, rather than the more expected plank-tonic algae bloom so common in most waters. A planktonic algae bloom will actually shade the water and inhibit filamentous algae growth until later in summer. These blooms are either not occurring in some ponds or occur at a much less density. Hence, filamentous algae upsurps the nutrients and explodes.

What can be done? Pond owners should be very vigilante about excess nutrients getting into their ponds. These nutrients can turn a tolerable algae density into a complete mess. Remember, algae of all types must get their nutrients from the water, not the pond bottom. Limiting nutrients levels in water limits algae abundance. Common sources of additional, unwanted nutrients are geese, lawn fertilization, inefficient septic systems, agricultural sources, and believe it or not, grass carp (white amur). Grass carp, via their digestion of plants they consume, release nutrients stored long-term in plants. These nutrients become available for algae growth. Unfortunately, grass carp are not very good at controlling filamentous algae. It's not a preferred food item.

Aeration can help, but will generally not eliminate the filamentous algae entirely. Bubble diffuser systems are preferred as they prevent pond stratification better than ornamental fountains. An un-stratified pond tends to have less filamentous algae because anoxic conditions in bottom waters releases phosphorus - a critical nutrient for explosive algae growth. Oxygenated bottom waters keeps the phosphorus "bound up". Also, a well circulating pond via aeration tends to promote planktonic algae, which enhances the food chain and ultimately the pounds of fish a pond can grow.

A lot of people ask about barley straw to control filamentous algae. Research from England was encouraging, but results from U.S. research projects have not achieved similar results. Thus, I'm cautious about it's use. For those who wish to buck the research results and try it, a new fact sheet is available via OSU Extension that provides guidelines.

The best chemical options are copper compounds, such as copper sulfate or chelated copper products. In April, May, and usually June, owners can use liquid formulations and eliminate all the algae with little risk of a fish kill. In July and onward, it is safest to use granular formulations and treat 25% of the problem every 10-14 days. In most cases, a fish kill will not occur.

Finally, keep in mind that a pond choked with filamentous algae and left untreated can also cause a fish kill. Respiration at night by the abundant algae, couples with hot, cloudy weather, can lower oxygen to dangerous levels in the pre-dawn hours.

Bill Lynch – Program Specialist 
                     OSU Extension

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Spruce Problems
For several weeks, the Diagnostic Clinic at OSU has been receiving samples of spruce (Picea spp.), primarily Norway spruce, from many areas of the state and all exhibiting similar symptoms. Samples have been examined from Preble, Fayette, Paulding, Greene, Fulton, Clark, Darke, Miami, Van Wert, Highland, and Mercer counties, with verbal reports from Henry, Washington, and Jackson counties.

On these samples, the newest growth, that which began to emerge in 2003, has withered, drooped and begun to dry out. Symptoms are limited to the new growth and are not progressing into last year's tissues. The descriptions which accompany these samples usually state that the symptoms are more severe, or are exclusively found on the south and southwest sides of the trees. The widespread occurrence of these symptoms and the uniformity of symptom pattern on affected trees point to a noninfectious, or abiotic, problem. The most likely cause of this is dessication resulting from high winds during the week of May 12. These winds may have occurred at a critical point in growth and development of the emerging candles; the developing candles were soft and lush and lost moisture more rapidly than the trees could replenish it. Although Norway spruce has been the predominant type of tree showing these symptoms, a few samples if fir, blue spruce, and hemlock have also been observed with similar symptoms.

The symptoms are very similar to those described for frost/freeze injury in references such as Diseases of Trees and Shrubs, by Sinclair, Lyon, and Johnson or the Forest Service's Christmas Tree Pest Manual. However, no widespread frost/freeze event occurred which would account for the damage being reported, and the pattern of damage being observed on individual trees is not consistent with frost/freeze injury. In some localized areas cold injury may have caused some initial damage which was intensified by the winds.

In reference to pines (Pinus spp.) be very careful when drawing the same conclusion regarding wind injury. Sphaeropsis blight (Diplodia tip blight) is active, and causes very similar symptoms in this genus. Sphaeropsis can occasionally infect spruce, as can some other pathogens. If symptoms begin to progress from the current year's tips into last year's tissues, an infectious agent should be suspected.

Since the damage to the spruces appears to be due to a one-time event which has passed, no treatment is recommended. Damaged tips my be pruned out, if desired.

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Sincerely,
 

Mike Hogan Extension Agent Agriculture & Natural Resources

Ken Simeral Extension Agent Agriculture & Natural Resources Community Development

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