Pasture and Forage Minute: Grazing in the Dog Days of Summer, Grasshopper Tips and Silage Storage Strategies
Summer Heat and Forage Growth
As we move into the heart of the summer, hot temperatures are common. How these temperatures affect our pasture and forage plants depends on the type of plants we are dealing with.
The two primary plant classifications are warm-season and cool-season and this is based on basic plant physiology and their specific photosynthetic pathway. Practically speaking, and as their names suggest, every plant species has a specific temperature range in which it maintains growth.
When it gets hot, 90-plus degrees, cool-season plants such as bromegrass, orchardgrass, fescues, needlegrasses and wheatgrasses all struggle and will have a very slow growth rate, even if there is plenty of moisture. If conditions are very dry, these cool-season grasses might completely stop growth and go into a summer dormant state.
High night temperatures also have forage quality implications for cool-season plants. They can cause rapid respiration rates, burning off valuable nutrients that plants accumulated during the day.
Warm-season grasses are just the opposite. Millet, sudangrass, sorghums and our native bluestems, gramas, switchgrass and other warm-season grasses thrive when the temperature is around 90 degrees. Their metabolism runs at peak efficiency when it is hot so they grow rapidly while maintaining reasonable forage quality and good root growth.
As you graze or hay, be aware of the stress weather is putting on your forage. When it’s too hot, allow plants a longer recovery period before the next grazing. And don’t expect high feed values or good animal gains when the nutritional goodies are burned right out of the plants.
Proper expectations and management adjustments can limit the stress from hot weather.
Grasshoppers in Alfalfa
We are starting to see populations of immature grasshoppers across the state. Stay tuned as I discuss how to evaluate your alfalfa fields and potential control options.
Grasshoppers can be damaging in high numbers to our alfalfa and hay fields. And they will only get worse as the summer continues. You may need control in your field.
Control begins with scouting to determine if insecticides are economically useful. Exact economic thresholds can’t be determined because of variables like value of the alfalfa and growth stage of both alfalfa and grasshopper. Still, if the grasshopper population in an established field is higher than five grasshoppers per square yard or 15 grasshoppers per square yard in field margins, insecticides probably can be worthwhile. New fields planted in late August are very susceptible to grasshopper feeding and treatment is probably needed if the grasshopper population is just half this level.
Around many fields, grasshoppers have just started moving in from the field margins. Treating just the outside 150 feet is probably sufficient in these situations. However, if the entire field is already infested, it usually is best to first harvest the alfalfa and then apply insecticide to protect the regrowth. There are several insecticides labeled for use on alfalfa.
To reduce the cost and amount of insecticide used when treating an entire field, harvest the alfalfa but leave several small, uncut strips across the field. The remaining grasshoppers will quickly congregate in these strips, enabling you to treat just these smaller areas.
Please be especially careful to avoid injuring bees and other important pollinating insects when using insecticides, and carefully read and follow all label directions. Some precautions you can take to protect bees include time of day when spraying, using less toxic insecticides and avoiding areas with blooming plants.
If you have many grasshoppers in your alfalfa, control them soon. As they grow larger, they’ll only get worse.
Corn silage harvest may seem like a long way off, but preparation for a successful harvest begins now. Improper silage storage and fermentation can result in losses up to 20% prior to feeding. Plan your storage now to keep excessive storage losses from happening to you.
Preventing oxygen from entering your silage should be a top priority when considering silage storage. Bagged silage is a versatile option that allows the storage location to move year to year. Placing the silage in a bunker is optimal for excluding oxygen, but make sure to check these structures for cracks and repair any that are found to maintain their integrity. If silage is a feedstuff on your operation, the reduction in losses that a permanent structure provides can offset the costs when spread out over several years.
Silage piles are the more traditional approach and can allow for greater volumes of silage to be stored in a smaller area. Oxygen exclusion in piles that lack a permanent structure can be enhanced with some planning. Before harvesting, line the sides with bales and place oxygen-limiting plastic down the sides and for several feet under the bottom to seal the sides of the pile. At a minimum, placing plastic on top of the pile is an investment worth the time, labor and money. By covering the pile, we can reduce oxygen from moving into the pile from the top and reduce precipitation exposure. Increased moisture can lead to spoilage, and result in the pile “weeping” and leaching out valuable energy and protein.
Corn silage is a valuable feed resource but suffers from high dry matter losses when stored incorrectly. Keeping oxygen out of your silage requires planning now. Pick an appropriate location for harvest and feed out success and store correctly to minimize feed losses.