Managing aquatic vegetation
By
John Grimes-
Managing aquatic vegetation without chemicals
Aquatic plants and algae are common to many of Ohio’s ponds and quite often attain abundances that cause problems for owners. Excessive plants and algae can interfere with swimming and fishing, upset the fish community‚s balance, clog pumps if present, and ruin the aesthetic value of the pond. Many pond owners have expressed a desire to manage their pond without the use of chemicals. Also, pending new federal rules may make using herbicides and algaecides in aquatic systems more difficult and expensive. So it seems relevant to consider how a pond’s plant community might be managed without chemicals.
Many pond owners do not realize that low amounts of aquatic plants are beneficial to the pond’s ecosystem. They can provide critical food and nesting habitat to a wide variety of fish and wildlife. Additionally, plants store nutrients long-term making them unavailable to algae and duckweeds. How much is too much?
Research has clearly demonstrated that when plant abundance exceeds 20%, the balance between largemouth bass and bluegills begins to skew in favor of bluegills. The end result can be a stunted bluegill population because bluegill have too many hiding places and bass cannot find them. The pond owner should set or re-assess his or her pond management goals and determine how much vegetation will be tolerated. In many ponds, little additional management activity may be needed.
Nutrient management
When a pond has excessive levels of aquatic plants and algae, it is almost a certainty nitrogen and phosphorus levels are or have been too high. Just like growing grass in your front yard, if a pond is fertilized with outside inputs of nutrients, more aquatic greenery will grow. The more nutrients, the bigger the problem. Common sources of unwanted nutrients are Canada geese, fertilizing grass around a pond, a septic system too close to the pond, domesticated animals in the watershed (even a few can be problematic), and agricultural runoff. It is recommended that pond owners experiencing plant or algae problems assess the potential of whether excessive nutrients can enter the pond and take corrective measures if possible. Watershed characteristics are an important component of nutrient management. A pond whose watershed is largely composed of natural vegetation will have fewer problems than a pond with an agricultural watershed. While nearby agriculture or domesticated animals may not be able to be relocated, the pond owner can take action.
Re-configuring the adjacent land so that agricultural runoff goes around the pond instead of into the pond can be a big help. Also, replacing mown, cool season grass between the pond and agricultural areas with native warm season grasses and prairie flowers can reduce nutrient inputs. Their deeper root systems hold water longer, allowing the grasses and flowers to absorb the nutrients that otherwise would go into the pond. These warm season grasses and prairie flowers are fantastic wildlife habitat.
Many pond owners who prefer not to use chemicals are willing to use pond colorants. Pond colorants are nothing more than food grade blue dyes. Some products have other colors mixed in. When used correctly, the colorants darken the water and reduce sunlight penetration.
Reduced light reduces the amount of aquatic plants and algae that will grow, often to levels acceptable to the pond owner. Pond colorants are most effective in ponds receiving very little runoff and flushing during rain events. Ponds with a large watershed or have a little creek entering them often lose their blue color after every rain and additional colorant is needed. This can get expensive. Pond colorants are most effective when initially applied in March.
Aeration
Outside sources of nutrients are a major problem for many Ohio ponds, but ponds with a lot of bottom muck (especially old ponds) can have phosphorus cycled internally which can cause algae and duckweed/watermeal blooms.
What causes phosphorus to be cycled internally? Pond stratification. Most Ohio ponds stratify, meaning a warm layer of water sits atop a cold layer of water during the summer and early fall.
Because these layers typically do not mix until mid-fall, the cold bottom layer loses its oxygen as decomposition of dying materials and bottom muck occurs. In the absence of oxygen, phosphorus from the bottom muck is released into the water where it can grow algae and duckweeds. An effective way to eliminate this internal release of phosphorus is to make sure oxygen is present along the bottom all summer. This can be easily accomplished with a bottom bubble aeration system. In such a system, bubbles push up bottom water to the surface while highly oxygenated water from shallow areas moves along the bottom to replace the rising deep water.
Many ponds in Ohio are effectively managed without chemicals each year. Typically bottom aeration and pond colorants are used, and the pond’s watershed retains most nutrients prior to water going into the pond.
Blossom end rot on tomatoes and squashes
Blossom end rot is a common problem on tomatoes, especially early ripening ones. This problem also affects plants in the squash family, particularly summer squash, as well as eggplant, peppers, and even some melons. Just near the time fruit ripens, a dry sunken decay develops on the blossom end (terminal tip) of the fruit. This is not caused by an organism but rather a physiological disorder associated with a low concentration of calcium in the fruits. Hold on, however, before applying calcium to the soil. Unless a soil test has been done and low calcium levels are reported, don’t apply calcium to the soil. In many cases, there might be plenty of calcium in the soil but it may be bound up in the soil, or is unavailable to the plant due to drought stress or excessive soil moisture fluctuations.
Foliar applications of calcium are often recommended. While one might think this works, they are of little value because of poor absorption and movement into the fruit where it is needed. The application of Epsom salts is also recommended but this does not remedy the situation either. Avoid drought stress and wide fluctuations in soil moisture by watering the plants in the morning, 2-3 times a week. This practice may lessen the problem, but will not totally solve the problem.
John Grimes is the Ohio State University Extension Educator for Agriculture and Natural Resources in Highland County.[[In-content Ad]]
Aquatic plants and algae are common to many of Ohio’s ponds and quite often attain abundances that cause problems for owners. Excessive plants and algae can interfere with swimming and fishing, upset the fish community‚s balance, clog pumps if present, and ruin the aesthetic value of the pond. Many pond owners have expressed a desire to manage their pond without the use of chemicals. Also, pending new federal rules may make using herbicides and algaecides in aquatic systems more difficult and expensive. So it seems relevant to consider how a pond’s plant community might be managed without chemicals.
Many pond owners do not realize that low amounts of aquatic plants are beneficial to the pond’s ecosystem. They can provide critical food and nesting habitat to a wide variety of fish and wildlife. Additionally, plants store nutrients long-term making them unavailable to algae and duckweeds. How much is too much?
Research has clearly demonstrated that when plant abundance exceeds 20%, the balance between largemouth bass and bluegills begins to skew in favor of bluegills. The end result can be a stunted bluegill population because bluegill have too many hiding places and bass cannot find them. The pond owner should set or re-assess his or her pond management goals and determine how much vegetation will be tolerated. In many ponds, little additional management activity may be needed.
Nutrient management
When a pond has excessive levels of aquatic plants and algae, it is almost a certainty nitrogen and phosphorus levels are or have been too high. Just like growing grass in your front yard, if a pond is fertilized with outside inputs of nutrients, more aquatic greenery will grow. The more nutrients, the bigger the problem. Common sources of unwanted nutrients are Canada geese, fertilizing grass around a pond, a septic system too close to the pond, domesticated animals in the watershed (even a few can be problematic), and agricultural runoff. It is recommended that pond owners experiencing plant or algae problems assess the potential of whether excessive nutrients can enter the pond and take corrective measures if possible. Watershed characteristics are an important component of nutrient management. A pond whose watershed is largely composed of natural vegetation will have fewer problems than a pond with an agricultural watershed. While nearby agriculture or domesticated animals may not be able to be relocated, the pond owner can take action.
Re-configuring the adjacent land so that agricultural runoff goes around the pond instead of into the pond can be a big help. Also, replacing mown, cool season grass between the pond and agricultural areas with native warm season grasses and prairie flowers can reduce nutrient inputs. Their deeper root systems hold water longer, allowing the grasses and flowers to absorb the nutrients that otherwise would go into the pond. These warm season grasses and prairie flowers are fantastic wildlife habitat.
Many pond owners who prefer not to use chemicals are willing to use pond colorants. Pond colorants are nothing more than food grade blue dyes. Some products have other colors mixed in. When used correctly, the colorants darken the water and reduce sunlight penetration.
Reduced light reduces the amount of aquatic plants and algae that will grow, often to levels acceptable to the pond owner. Pond colorants are most effective in ponds receiving very little runoff and flushing during rain events. Ponds with a large watershed or have a little creek entering them often lose their blue color after every rain and additional colorant is needed. This can get expensive. Pond colorants are most effective when initially applied in March.
Aeration
Outside sources of nutrients are a major problem for many Ohio ponds, but ponds with a lot of bottom muck (especially old ponds) can have phosphorus cycled internally which can cause algae and duckweed/watermeal blooms.
What causes phosphorus to be cycled internally? Pond stratification. Most Ohio ponds stratify, meaning a warm layer of water sits atop a cold layer of water during the summer and early fall.
Because these layers typically do not mix until mid-fall, the cold bottom layer loses its oxygen as decomposition of dying materials and bottom muck occurs. In the absence of oxygen, phosphorus from the bottom muck is released into the water where it can grow algae and duckweeds. An effective way to eliminate this internal release of phosphorus is to make sure oxygen is present along the bottom all summer. This can be easily accomplished with a bottom bubble aeration system. In such a system, bubbles push up bottom water to the surface while highly oxygenated water from shallow areas moves along the bottom to replace the rising deep water.
Many ponds in Ohio are effectively managed without chemicals each year. Typically bottom aeration and pond colorants are used, and the pond’s watershed retains most nutrients prior to water going into the pond.
Blossom end rot on tomatoes and squashes
Blossom end rot is a common problem on tomatoes, especially early ripening ones. This problem also affects plants in the squash family, particularly summer squash, as well as eggplant, peppers, and even some melons. Just near the time fruit ripens, a dry sunken decay develops on the blossom end (terminal tip) of the fruit. This is not caused by an organism but rather a physiological disorder associated with a low concentration of calcium in the fruits. Hold on, however, before applying calcium to the soil. Unless a soil test has been done and low calcium levels are reported, don’t apply calcium to the soil. In many cases, there might be plenty of calcium in the soil but it may be bound up in the soil, or is unavailable to the plant due to drought stress or excessive soil moisture fluctuations.
Foliar applications of calcium are often recommended. While one might think this works, they are of little value because of poor absorption and movement into the fruit where it is needed. The application of Epsom salts is also recommended but this does not remedy the situation either. Avoid drought stress and wide fluctuations in soil moisture by watering the plants in the morning, 2-3 times a week. This practice may lessen the problem, but will not totally solve the problem.
John Grimes is the Ohio State University Extension Educator for Agriculture and Natural Resources in Highland County.[[In-content Ad]]