Southern Ponds & Wildlife Vol. 3 #1 (Winter 2004)
Don C. Keller
Every spring during the months of April and May, I get hundreds of calls from pond owners who seem to be overwhelmed with vegetation problems. They usually state that they began fertilizing in March and had difficulty establishing a desirable plankton bloom (green color). What they fail to say is that there was some vegetation in the pond when they began fertilizing. The reason they couldn’t get a bloom was because the vegetation was sucking up the fertilizer.
All vegetation responds to fertilizer, sunlight and moisture. When you go to your pond in late February or early march to begin fertilizing, you should first walk around the pond perimeter and see if you observe any unwanted vegetation growing in the shallows. If you don’t see any, but you have had a problem in the past, I suggest you take your casting rod and tie on a weighted lure, cast out to the deep water, and drag it slowly across the bottom. If it comes back clean, go ahead and start fertilizing.
I have seen some lakes that did not have vegetation on the edges but would have rooted plants growing in 6-8 feet of water and were difficult to see from the shoreline. Once these lakes were fertilzeed, the vegetation seemed to explode and would soon top out at the surface. Weed treatment then becomes very expensive and may have to be handled by a professional.
If vegetation is observed, the first thing you should do is get a sample and have it identified. Place your sample in a zip lock bag and send it to a fisheries consultant. Once plat is identified, a chemical treatment can be recommended. Almost all herbicides are ineffective until the pond water reaches 55-60 degrees F.
I have often heard the statement from perplexed pond owners’ “I thought that if I fertilized, I wouldn’t have a moss problem.” Well, this is partially true. The main purpose of a fertilization program is to increase the food supply available for your fish. This is done by first creating a phytoplankton bloom, which imparts a green color to the water. This green color also creates a shading effect which blocks sunlight and prevents unwanted vegetation from developing if none were present when the fertilizing began.
Grass carp are a very useful tool but keep in mind that they are cold blooded and their body temperature will be the same as the pond water. Therefore they will eat much more when the water temperature warms up. If you wait for them to clean up the weeds, you may have to delay fertilization for several months, which will also slow the growth of you sport fish.
• Visit the pond and see if any vegetation is present.
• If vegetation is found have it identified and treatment recommended.
• Check water temperature and treat once the water warms to 55-60 degrees F.
• Add grass carp to prevent the problem from re-occurring.
• Begin fertilizing when the weeds are dead or disappeared.
• Remember, A stitch in time saves nine!