Dwain W. Meyer

Extension Forage Specialist

Drought in central and western North Dakota has reduced the forage yield of perennial forages like alfalfa, alfalfa/grass mixtures, and pure grasses like brome and crested wheatgrass. Conservation reserve program (CRP) acreage was recently released, which should help producers meet their forage needs. If there is inadequate CRP acreage in your area or a higher-quality forage is needed, consider warm season annuals.

Common warm-season annuals are foxtail or proso millets, sudangrass or sudan/sorghum crosses, and pearl millet. Pearl millet’s major advantage is the lack of HCN or prussic acid, but pearl millet is the poorest choice for North Dakota. Forage yields in southeastern North Dakota have been equal or maybe slightly greater than sudan/sorghums, but generally lower yielding than the sudan/sorghums in the rest of the state. Forage yield of foxtail or proso millet, sudangrass, and sudan/sorghums under a one-cut systems have been fairly similar with maybe a slight advantage to the sudan/sorghums. Forage yield will be substantially greater with sudangrass and sudan/sorghums than foxtail or proso millets when rainfall permits a second harvest. The major disadvantage of sudangrass and the\ sudan/sorghums is the presences of HCN (hydrocyanic acid). Under drought conditions, HCN can build to potentially toxic levels when rainfall restricts growth to less than 20 inches. If the sorghums are hayed under these conditions, be sure to get the forage tested for potential problems. Rarely will HCN be a problem in a hay or silage crop if the plant height is greater than 20 inches since maturity and the drying for hay and handling the silage after fermentation reduces the HCN in the forage. Grazing sudangrass or sudan/sorghums less than 20 inches under drought is the major concern for possible HCN poisoning. Piper sudangrass has been the standard sorghum used in North Dakota. Piper is an open-pollinated sudangrass known to be lower in HCN. Sudangrass hybrids and sudan/sorghums will be higher in HCN. In recent years, the BMR (brown midribbed) sudangrass, pearl millet, and sudan/sorghums have been released. The BMR character reduces the lignin content of the plant, which increases the digestibility and animal performance compared with non BMR species. The major rap on BMR sorghums or pearl millet has been that they are considered lower yielding, but preliminary data in North Dakota does not show this yield drag. If considering a sorghum, I suggest considering the BMR types.

A major problem with sorghums and pearl millet is getting good-quality hay. The sorghums should be hayed at 2.5 to 4 feet in height. The large stems at this height makes it very difficult to get proper drying to preserve the forage in the bale. Always use a hay conditioner to either crush or break the stem to speed drying and be careful to reduce the size of the window, especially when the crop is heavy, to facilitate drying. Pearl millet does dry better than the sorghums since it has a greater leaf to stem ratio compared to the sorghums. Foxtail millet, both siberian and german, and occasionally proso millet are commonly grown in North Dakota as emergency forage crops. Manta siberian millet is the most common species grown due to its drought tolerance. German millet is slightly latter maturing and higher yielding under good rainfall. Forage quality of foxtail millets tends to be the poorest of the common warm-season annuals and they may cause a diuretic action in livestock. Foxtail millets should never be feed to horses. Proso millet, commonly used as a grain crop, sometimes is harvested for forage. Due to the grain, forage quality is higher in proso than foxtail millets. Cool-season forages like oat, barley, and triticale probably should not be planted in June or July. The warm summer temperatures forces maturity and reduces tillering causing poor forage yields. If considering a cool-season forage, Paul oat has performed the best. Recent

Wisconsin data indicates that a late seeding of oat (about August 1 to 15) produced 1 to 2 tons of hay with good quality. If rainfall is inadequate to seed warm-season annuals, consider this late seeding if soil moisture is adequate.

Jeff M. Stachler

Assistant Professor - Sugarbeet Weed Science

The goal of all growers should be to maximize glyphosate activity whenever it is applied to glyphosateresistant crops. This goal should maximize profitability and weed control, and reduce the risk for herbicide resistance. Below are the most important management strategies for improving glyphosate activity. For additional information, consult pages 68 and 69 in the 2008 North Dakota Weed Control Guide.

1. Apply glyphosate to small (< 4") annual weeds.

2. Apply glyphosate to perennial species in the bud to early-flowering stage of development.

3. Apply the most effective rate for the most difficult to control species in the field. For many annual species the minimum rate of glyphosate should be 0.75 pounds acid equivalent/acre (lb ae/A). Species such as lambsquarters, velvetleaf, wild buckwheat, common ragweed, common mallow, smartweeds, horseweed/marestail, and waterhemp can be difficult to control with glyphosate. Consider using the maximum single-use rate of glyphosate for these species, especially if a reduction in control has been observed over time. Rates of glyphosate greater than 0.75 lb ae/A usually improves control of perennial species, compared to lower rates. Multiple glyphosate applications can also improve control of perennial species.

4. Always add ammonium sulfate (AMS) to glyphosate mixtures. Ammonium sulfate should be added at a minimum of 4 pounds per 100 gallons of spray mixture (lbs/100 gal) for most of North Dakota. Add additional AMS if water hardness is greater than 1600 ppm.

5. Allow at least a 6 hour rainfast period for all glyphosate formulations for maximum activity. A shorter rainfree period can be acceptible for the most susceptible species. Lambsquarters control is usually reduced if the rainfree period is less than 6 hours.

6. Apply glyphosate during the warmest and most humid weather conditions to maximize activity.

7. Most glyphosate formulations include nonionic surfactant (NIS) at a high enough concentration for maximum activity. However, some glyphosate formulations do not include NIS. For these formulations add a quality NIS product at 0.5 to 1.0% v/v. Some weed species, especially lambsquarters, may be more effectively controlled with the addition of NIS at 0.25 %v/v to "loaded" glyphosate formulations. Know which glyphosate formulations prohibit the use of additional NIS.

8. Glyphosate activity is influenced by the time of day of the application. Maximum activity occurs between 10:00 AM and 4:00 PM. Velvetleaf and common ragweed control may be the most negatively affected by the time of the glyphosate application.

9. Application of glyphosate in low water volumes improves glyphosate activity. However, when spraying large weeds and/or dense weed canopies, higher spray volumes usually improves glyphosate activity.

10. Glyphosate is strongly and irreversibly absorbed to clay particles and organic matter. Therefore dust of any amount, especially initiated by the wheels of the sprayer, will cause a reduction in glyphosate activity. The best methods for decreasing this problem are to drive slower and put higher volume nozzles in the boom over the wheels. These solutions will not completely solve the problem and growers must remember to not apply greater than the single-use rate of glyphosate when using the higher volume nozzles.

11. When mixing other herbicides with glyphosate, add the most effective adjuvant for that herbicide being added. This strategy will maximize the activity of the herbicide being added to the glyphosate mixture. If the alternative herbicide recommends the addition of an oil adjuvant for maximum activity, add only Superb HC or Destiny HC at 0.5 %v/v to the mixture with glyphosate. The reason for this is that most oil adjuvants antagonize glyphosate activity.

Kasia Kinzer

NDSU Plant Diagnostician

NDSU.PlantDiagnosticLab@ndsu.edu

701.231.7854

Part of my lawn is almost entirely shaded. It lies under a huge silver maple (probably the biggest in Fargo!), and it is on the north side of my house, surrounded by a tall fence. This particular patch of lawn gets very little sun and even less air-flow. So, it should come as no surprise to me that my nice green lawn turns whitish-blue every year under cool, humid conditions. I noticed the white powdery growth coating my turf leaves, and it seemed to have appeared over night! This patch of lawn annually suffers from a disease known as powdery mildew. The close-up image shows infected blades of a lawn (from a newer lawn in West Fargo; photo by Sam Markell).

Powdery mildew diseases affect many different plants, including ornamental plants and field crops. The various related fungi that cause these types of diseases are fairly host specific, so, for example, a fungus that causes powdery mildew on lilac will not cause powdery mildew on turf. Below is a standardized report that you might receive in the mail if you submit an ornamental sample afflicted with powdery mildew:

"The sample is infected with a powdery mildew disease. The fungi that cause these types of diseases are fairly host specific, so it is unlikely that unrelated plants will be affected by the same genus and species of fungus causing powdery mildew on the sample. Powdery mildew diseases are common on many trees and ornamentals, often occurring in plantings that are concealed in dense shade or have poor air circulation due to many trees, shrubs, or fences. The disease is favored by cool, humid weather, and high levels of nitrogen. Free moisture (dew) is not necessary for powdery mildew fungi to infect the leaves, so infection can occur even during dry periods as long as humidity is high.

Powdery mildew diseases can be managed by improving aeration, by planting species in appropriate sites to reduce stress (for example, sun-loving plants should be planted where they get adequate sunlight), and by using resistant varieties when possible. Often, pruning and thinning surrounding trees and bushes can help minimize disease development. Fungicides are not typically recommended for powdery mildew diseases in the landscape. Some

fungicides may help with the control of this disease, but most fungicides available to the homeowner do not cure already infected plants; most only protect \leaves from new infections. Fungicides may be available at lawn and garden centers, but they must be applied season long or as long as weather conditions favor disease, and they will not cure powdery mildew diseases by themselves. As a result, the use of fungicides is seldom warranted for managing powdery mildew in a landscape. Neem oil or sulfur may also be somewhat successful in controlling this disease by protecting new growth from infection. If chemical control is used, be sure to read, understand, and follow the label instructions carefully to avoid injury to yourself, the plant, or the environment."