Friday, July 20, 2012

The good, the bad and well, the bad

It has been a while since the last post and much has happened in the interim. As expected, giant salvinia present on the lake this winter was simply waiting for warmer weather to really get going....and it didn't take long.

Before we get to the bad news, lets highlight some positives. Giant salvinia collected on the lake in early February 2012 was processed and live weevils were found in the plant material. Granted, there weren't that many but some were alive and well and we certainly see that as a success. Samples collected again in April also produced a couple live weevils. The numbers were much fewer than in February, but between the two sampling dates, large rains and high water move the salvinia around and further dispersed the weevils.

Salvinia collection in early April. Dr. Allen Knutson collects salvinia in the front of the boat and Mr. Lee Eisenberg records data in the back.

As seen in the photo above, large mats of giant salvinia 10 to 20 acres in size were starting to form in the Clinton Lake area by early April (this is part of the bad news in case you were wondering!). With this information in hand, the wheels were put in motion to begin the fight against giant salvinia early in the year using any means available.

Beginning in May, large scale chemical applications began on Caddo Lake. The Cypress Valley Navigation District began treating vegetation along boat roads and in other critical areas to protect lake access and navigation. In addition, the Center for Invasive Species Eradication contracted with SprayCo to treat the large giant salvinia infestation in the Clinton Lake area. Over the course of May and June, SprayCo treated approximately 696 acres of giant salvinia. It would be fantastic if we could say that we got all of the salvinia treated and killed, but we cannot (this is also the bad news).

Also used in to fight giant salvinia are the salvinia weevils being grown at the Caddo Lake National Wildlife Refuge at the our weevil rearing facility there. Under the direction of Mr. Lee Eisenberg, two harvests and releases have been made this spring. On May 22nd and 23rd, approximately 31,300 adult weevils and countless larvae and eggs were release in the Bird Roost area. On July 18th, another batch of weevils were released near the first release site. This site is being used as a nursery area for the weevils due to its remote location, limited boat traffic and the fact that flood waters usually push salvinia out of this area into other parts of the lake. The thought is that flood waters will naturally disperse weevils across the lake once they are established in this area.

Mr. Lee Eisenberg harvests weevil infested giant salvinia at Caddo Lake NWR weevil rearing facility on July 18, 2012 for distribution on Caddo Lake.
So as the summer continues, the fight will continue with everything and the kitchen sink being thrown at this stuff. 

No comments:

Post a Comment