«Aquatic Plant Management Barley Straw for Algae Control Carole A. Lembi, Professor of Botany Botany and Plant Pathology, Purdue University E-mail: ...»
The effectiveness of the straw is reduced by sediments suspended in the water (i.e. “muddy” water). Therefore, a higher dose may be required in “muddy” lakes or lakes with extremely severe algae problems. In these types of lakes, apply 450 pounds per acre (1.7 oz. per 10 square feet), but do not exceed 900 pounds per acre (3.3 oz. per 10 square feet). The decomposition of the straw requires oxygen, and the application of excessive amounts (greater than 900 lbs. per acre) of straw could reduce the oxygen content of the water to levels that stress or kill fish.
Example: Determining the amount of straw required to treat a 5 acre lake.
(2) The selected dose is 225 lbs of straw per acre.
(3) Multiply the area of the lake (in acres) by the amount of straw required per acre to calculate the total amount of straw required to treat the whole lake (5 acres x 225 lbs/acre = 1125 lbs).
(4) To calculate the number to bales needed to treat the lake, divide the total amount of straw required to treat the whole lake by the weight of a single bale of barley straw. For this example, assume one bale weighs 45 pounds. However, the size and weight of bales can be highly variable. It is recommended that the approximate weight of the bales be determined at the time of purchase (1125 lbs ÷ 45 lbs/bale = 25 bales).
How to Apply the Straw (1) The straw bales must first be broken apart. Bales are packed too tightly and do not allow adequate water movement through the straw.
(2) The loose straw should be placed in some form of netting. In larger lakes and ponds, CAPM suggests wrapping the straw in the cylindrical netting commonly used for wrapping Christmas trees (Figure 1). This netting can be used to construct straw-filled tubes (Figure 2) up to 65 feet long that contain about 110 pounds of straw. Loose woven sacks (e.g., onion sacks) can be used in small ponds that require low doses (Figure 3).
Figure 1. For treatments of larger ponds, barley straw can be repacked using a Christmas tree baler to feed the straw into a mesh bag.
Photo courtesy of Steve McComas, Blue Water Science, St. Paul, MN.
Figure 3. For treatments of small ponds, barley straw can be repacked into 50-lb onion mesh bags.
These bags hold about 7 pounds of barley straw. Photo courtesy of Steve McComas, Blue Water Science, St. Paul, MN.
(3) Use floats to suspend the straw-filled netting in the upper three to four feet of the lake. The straw will lose its effectiveness if it sinks below this depth. Water movement near the surface will keep the straw well oxygenated and distribute the growth inhibiting chemical throughout the upper portion of the lake. This ensures that the chemical is produced where the majority of the algae are growing and away from the bottom sediments that will inactivate the chemical. Therefore, it is recommended that floats be inserted inside the netting at the same time the netting is filled with straw. The netting is then anchored into place using rope attached to bricks or concrete-filled buckets.
Where to Apply the Straw
In order to improve the distribution of the growth inhibiting chemical, CAPM recommends placing several small quantities of straw around a lake. Place each net of straw roughly equidistant from other nearby nets and the shore. The placement of the nets does not need to be exact and practical considerations such as corridors for boating and angling may influence the location of the nets. In small ponds, where only one net of straw is required, place the net of straw in the center of the water body.
Sources of Netting
Sources of Cited Research/Information:
(1) Daniel E. Terlizzi, Maryland Sea Grant Extension Program, E-mail: firstname.lastname@example.org (2) John C. Holz, University of Nebraska, E-mail: email@example.com (3) Joseph E. Morris, Iowa State University, E-mail: firstname.lastname@example.org (4) Kenneth Langeland, University of Florida, E-mail: email@example.com (5) Stratford Kay, North Carolina State University, E-mail: firstname.lastname@example.org (6) Steve McComas, Blue Water Science, St. Paul, MN, E-mail: email@example.com (7) Steve Enger and David Wright, Minnesota Department of Natural Resources, St. Paul, MN, E-mail: firstname.lastname@example.org and email@example.com
The author of this publication, the persons cited herein, and Purdue University have provided this information for educational purposes only. In no way should the material be considered legal advice nor is any liability assumed for use of this information. No legal department of any agency has approved the content of this publication.
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