Matthew F. Stephens
County Agent, Jackson Parish
Everyone always welcomes spring with open arms. It is that small window between “too cold” and “too hot” to enjoy outside activities. It is also time to take care of recreational farm ponds. You also may want to deter some summer problems before they become too large to handle. Fertilization and weed control are two management practices that will make for a much more enjoyable summer if they are accomplished in the spring.
Fertilize if Desired
A fertilization program can greatly increase the fish production in fishing ponds. Adding nutrients stimulates the growth of the microscopic plants (algae) that feed the small animals that feed the fish.
Fertilization can increase fish production, resulting in more and bigger fish in properly managed ponds. Carefully considering whether or not your pond would benefit from a fertilizer program is important. Once a fertilization program is started, it should be continued each year, because the total weight of fish in the pond will increase, and the fish will come to depend upon the additional food resulting from fertilization. Ponds that already receive nutrients from the watershed usually do not need additional nutrients. Do not fertilize ponds that are fed commercial feed, ponds that are muddy or weedy, ponds with existing dense plankton blooms, ponds where the fish population is out of balance or ponds that have excessive water flow.
If you decide to fertilize, begin applications in the spring when the water warms above 65 degrees Fahrenheit. This has historically been during early to mid spring. This timing promotes the growth of algae before aquatic weeds can become prolific. Once the pond fertilization program is started, it should be maintained until water temperature falls below 60 degrees Fahrenheit. This is usually during mid to late fall.
Control Weeds
Chemical control of aquatic weeds should be the last resort in weed management, but when necessary, start in the spring before weeds get out of hand. Make sure to accurately identify the problem weed, since herbicides vary greatly in their effectiveness for different species. Herbicides that effectively control broadleaf species will not control grass type species.
Spot treatments of weedy areas usually can be accomplished without problems. When whole pond treatments are required, actually measuring the pond area is important. To visually estimate the area of a pond is amazingly difficult, even for “experts,” but it is necessary to get an accurate estimate so that herbicide dosage can be calculated correctly. Some herbicides are unsuitable for spot treatment, so check the label.
Decomposition of weeds killed by herbicides removes oxygen from the water and can result in a fish kill, especially in the summer months. When using a fast-acting herbicide, treating only a section (up to a quarter of the pond area) at a time will reduce the chances of oxygen problems. Unless the herbicide is intended for whole pond application, treating only a portion of the weeds at a time allows affected weeds to decompose before the next application.
Aquatic weeds should be differentiated from aquatic algae. Some algae may resemble weeds and will not be controlled with an herbicide. Some weeds resemble algae and will not be controlled with an algaecide. Algae, when killed, will also use oxygen to decay in the pond and can deplete much needed oxygen, so use extra caution when treating ponds during the spring and summer months.
If you are not sure of what aquatic weed specie is in the pond or if it is a weed or algae, contact your local LSU AgCenter Cooperative Extension Office or visit the LSU AgCenter Web site.