Huge problem with Raft system. HELP!!!

[Mathew Slattery]

My current system at home has-been running for about 2 years now and we are getting great result in both our raft and media beds.

A friend asked me to build him a small hybrid raft media system,which I did. The media beds have been running for just over a year and are doing great. I built the raft beds a few months later and they have been running for about 6 months. they started off well and have just gone down hill ever since. Everything is super deficient, and they are not growing well at all. There is a bad leaf hopper and thrip outbreak that I am trying to get under control but i don't believe that is the only problem. the root growth is also horrible. the system is exactly the same as my home system so I just can't figure out what is wrong.

Any help would be great. I am attaching photos below.

IMG_20140624_082916.jpg

IMG_20140624_082906.jpg

IMG_20140624_082748.jpg

IMG_20140624_082817.jpg

IMG_20140624_082805.jpg

IMG_20140624_082840.jpg

[Mathew Slattery]

Thanks for the information. What do you recommend I do? I live in the tropics and we are entering our warmest and wettest months and bugs seem to be going crazy. This is not in a greenhouse. They are only under small shade hoops.

[Vlad Jovanovic]

The images of that end in the digits 16 and 48 (the lettuce), look like typical crown rot issues...caused by an oomycetic/fungal pathogen. I bet if you look at the portion of the plant where the stem meets the roots (crown) it has turned to a brownish-red mush.

Poor greenhouse hygene, high temps, and things being too wet at the seedling stage are some of the most typical vectors, as is damage by insects...particularly thrips which like to hang out in the crown area doing their thing...creating little wounds which are inroads for disease. (They also are known to carry and transmit about 20 different plant viruses...but the damage you have is not symptomatic of any virus, but rather caused by an oomycete).