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Lettuce Disease

Hi Everyone,

We have had a lettuce disease that is running rampant through our crop and would love some help in identifying the disease. It was first noticed about a month ago and has since become more of a problem. It progresses from the outer leaves inwards. Any help will be much appreciated! Thanks!

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Super Green Thumb
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Joined: Sun Feb 15, 2009 11:04 pm
Location: TN/GA 7b

Re: Lettuce Disease

Since I don't know what variety of lettuce you are growing or what it is supposed to look like, I can't tell if there are any disease symptoms. Many leaf lettuces ordinarily look as pictured.

You always need to tell us where you are located. There are hardly any garden questions that can be discussed without regard to location/ climate/ weather. Are you in the Northern Hemisphere where it is late summer and hot? Lettuce is a cold weather crop that does not do well in the heat.
Twitter account I manage for local Sierra Club: Facebook page I manage for them: Come and find me and lots of great information, inspiration

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Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Re: Lettuce Disease

It looks more like insects and less like a disease. At this time of they year all of them are out in force. If you can get a magnifying glass or better yet a microscope, it would be good to look on the underside of the leaf and see if you can find any bugs crawling around. If you have a master gardener office near you, call them they will do pest id for you if you bring the sample in. I have a hand loupe, it comes in handy but it does require patience and some skill to get used to using it in order to focus and you have to move all around the leaf until you find something.

My guess is that they are aphids. Although at this time of the year thrips, whiteflies, and mites are also around and you may have more than one problem.

if you have ants around, put out ant bait.
You need very good sanitation. Get rid of the sickest plants and leaves and make sure you get rid of any leaves that drop.
Natural predators would be ladybugs.
If you have to spray, you can use insecticidal soap or neem oil. It will have to be done weekly.
Unless the problem is still small, I usually get rid of all the lettuce and sanitize the area as much as possible. Since aphids have multiple hosts, if I spray, I spray everything nearby. I plant lettuce in a different location next time and I usually wait a month before I will do that to make sure the aphids are gone. Sick lettuce rarely gets better and it is a short crop so I usually just start over.
Happy gardening in Hawaii. Gardens are where people grow.

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