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On May 23, 2018

To Cut Hay At The Proper Height

While many parts of Pennsylvania have yet to take a cutting of hay in 2018, in Southeastern Pa farm the first cutting alfalfa/orchardgrass was made last week. As you head to the field this year, Extension Agronomist Dwane Miller reports it’s important to pay attention to cutting height in your hay crop.

One of our goals as farmers is to maximize our yield; however, cutting a hay crop too low can lead to several negative issues. The introduction of the disk-type mowers (discbines) allows for cutting very close to the ground. Miller has seen many fields that have been “scalped” right to ground level. This differs considerably from the older sickle bar mowers (haybines), whose technology required some level of stubble height remain. Stand longevity can be compromised when the crop is cut too low. As a general rule, alfalfa can be cut closer to the ground than our grass hay crops. We need to think about where energy reserves are stored in the crop. For alfalfa, carbohydrates are stored below ground in the taproot. Our grass hay crops store their energy above ground in the stem base or tillers. Frequent mowing at a close height will continue to deplete these energy reserves, resulting in stand longevity issues.

The second consequence for mowing too close to the ground is increased ash content of the forage. All forage has a natural ash content of approximately 6%. However, mowing too closely with disk mowers can add soil to the crop, and increase the ash content by as much as 10-12% (18% ash content in total analysis). If we all had table-top smooth fields, it would also be much easier to make a closer cut across all fields. However, things such as groundhog holes and the unevenness of fields can add to increased ash content of our harvested forage.

So, the million dollar question is how low can you go? The best answer is…it depends! The first question Miller always asks is – is it a solid stand or a mixed stand? If you have grasses involved, you must keep cutting height higher than a pure stand of legume, if you want to keep the grass in the stand.

For Alfalfa or Clover best is a 2” minimum. Some literature shows a cutting height of 1” will not reduce stand longevity, but remember the increased ash content issue. Also, keep in mind that frequent cutting at early maturity will continue to deplete carbohydrate reserves. One cutting of alfalfa should be allowed to reach the bloom stage each year.

For Cool Season Grasses (Orchardgrass, Timothy) 4”during the establishment year and 3” minimum during production years. This is where we see most of our stand longevity issues. Frequent cutting of cool season grasses at a low height will continue to deplete energy reserves.

With mixed stands you must manage for the predominant species. Do you have a grass stand with some alfalfa, or an alfalfa stand with some grass? For alfalfa with some grass: 2.5 minimum”, fo grass with some alfalfa: 3” minimum (if you want to keep the grass stand!)

 

To Scout For Black Cutworm Moths And Slugs

Now that Spring has arrived in earnest, various pest species are active and they should be kept in mind. These pests include alfalfa weevil, timothy mites, cereal leaf beetle, black cutworms, and slugs, and we have addressed all these pest species in our newsletter in recent weeks. The latter two species tend to be perennial concerns, and for that reason we pay closer attention to them.

Extension Entomologist John Tooker explains Penn State Extension and the Department of Entomology are again using pheromone traps to monitor for arrival of black cutworm moths across Pennsylvania. For the most part, our traps are only detecting small numbers of moths; but we will continue to monitor and will share with you what we find.

As a reminder, black cutworm caterpillars are best managed with Integrated Pest Management, which in this case means with a combination of scouting and rescue treatments if populations exceed economic thresholds. (The economic thresholds are 2, 3, 5, and 7 cut plants per 100 seedlings for seedling, V2, V3, and V4 stage plants, respectively.) Rescue treatments, not preventative sprays remain the most efficient and economical tactic for managing black cutworm. For more information, see our factsheet (http://ento.psu.edu/extension/factsheets/black-cutworm).

As for slugs, they are becoming active, particularly in no-till fields, with juveniles hatching from eggs. In areas that have received rain recently, or in fields that tend to lie wet, these happy slugs may cause damage as corn and soybeans emerge. For growers who see an impending problem from healthy slug populations, it might be useful to consider delaying planting until soil temperatures are warm enough for corn or soy to jump out of the ground when it is planted. Nothing exacerbates slug problems like a crop that is slow to emerge and lethargic given cool temperatures.

To prepare for potential slug damage, it can also be helpful to have some slug bait on hand to use as rescue treatments in portions of fields being damaged.

Quote Of The Week: “Every man’s happiness is his own responsibility.” Abraham Lincoln