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Blight/Leaf spot disease?

Discussion in 'Outdoor Marijuana Growing' started by clodhopper, Feb 22, 2011.

  1. #1 clodhopper, Feb 22, 2011
    Last edited by a moderator: Feb 22, 2011
    I belong to a number of cannabis forums and one of the biggest outdoor issues for the past 2 years has been the appearance of leaf spot disease or late blight. Outdoor cannabis crops in the NE US, the midwest, mid atlantic and southern US have been totally devestated by the disease and many outdoor growers across the eastern part of the US have concluded that if the disease cant be killed, it will end outdoor growing in the eastern US. The disease has reduced my annual yeild from about 20lbs, to 4lbs and Im desperate to find a safe fungicide.

    The disease starts in late july/aug with yellowing of leaves and then quickly defoliates and kills the plant.

    Im shocked that its not a big topic in this outdoor section and im wondering why? I cant find it mentioned anywhere and it is litterally the biggest outdoor growing topic im aware off. I interact with more than 20 growers around the eastern US, and everyone of our crops are being destroyed by this disease.

    Have you guys found a cure?
  2. I'm sorry to say I haven't (though I am new to growing) however I don't think it is a natural occurrence if it only began recently and in different parts of the country that have different climates.
  3. hey clod... yes these past 2 years have hit hard with blight.. i will be using some beneficial bacteria this year as well as some liquid silca foliar applications to try and prevent any mildew or blight.. maybe it will slow down this year?:eek:
  4. #4 clodhopper, Feb 24, 2011
    Last edited by a moderator: Feb 24, 2011
    Gosh i hope so t7s. I too am going to give the serenade argraquest a try.
    Serenade® MAX : Fungicides : AgroChemical :Agraquest

    Its the same disease family as "late tomato blight". Ive talked to ag/gardening experts and chemical experts and all pointed me to Liquid Copper and last year thats what i used. It was indeed a cure for the disease in most strains, and if i had discovered it earlier, it would have saved my crop.

    caveat? Im afraid of the LC. It is a heavy metal and doesnt dissipate. It washes off of the plant and the label says 2 weeks or until it rains, but it worries me. It is used to treat blight in leaf lettuce, cauliflower, potatoes and other vegatables and is OMRi listed, but im still woried about using it. Copper poisoning is very serious shit and when it washes off of the plant it will remain and build up in the soil........ but its organic!!!!

  5. dude that looks like a good product in the link. you using in your soil? and yeah i stay away from liquid copper for sure.
  6. Soil and surrounding vegetation t7s. The diesease is laying dormant in dead weeds and vegetation around the plant just waiting for the right conditions to appear.

    I will alter bi weekly applications between serenade and Greencure, for a wide spectrum of action. Greencure is really a good product too, but it only last about a week.
  7. Did you just start seeing this blight/leaf spot or has this been on-going for awhile? Here in the midwest I have been fortunate not to have experienced any fungal problems. Just wondering (you probably have already done all of this): have you abandoned your old growing spots and tried new areas? Are you reusing containers that may have not been washed or rinsed? Are you composting from the same container year after year? Do you remove and dispose of the infected plant leaves and stems? Water only in the mornings? Fungal pathogens tend to stay in the soil for quite some time and sometimes the best way to combat it is just to let that area "rest" for a few years. I wish you good luck this growing season.
  8. Ah, "best practices" JPG.

    No, i havent abandoned my old sites and cant. I grow individual plants in different sites. Ive used many of these single spots for over 20 years, each year at harvest time, i cut the plant and work in 3 galllons of compost. Over the years, the holes have become rich. Good sites dont come easy but you are correct JPG, it lives and waits in the soil. Im drenching this year with Actinovate, which is a soil treatment.

    I cant remove the dead vegetation because im in the bush and high weeds. I do spray the adjoining area and the soil, but thats about all i can do.

    You are lucky JPG. I know guys in Michigan, illinois,ohio and mossouri that have been devastated by the disease. You seem familiar with it. I grew for years here and never had a problem and then 2 years ago, bamm! crop destroyed. The second year yeild was reduced by 60%.
  9. No shit?! That last paragraph chilled me. I don't want to have to deal with that stuff, but you're right, it is not far away. In the last two years, I have heard reports from neighbors who have friends that have vegetable gardens on the other side of the city, and can't grow tomotoes because every year they get hit with tomato blight. What blows me away is that I didn't know that mj plants were susceptible to getting stem/leaf blight, as you mentioned. Years ago (20 years ago :eek: i just realized) I've worked on ginseng research farms that were trying to develop fungicides to stop phytophthora - nothing seemed to really work. Perhaps nowdays fungicides have gotten better, and safer, and your crop will turn out well. Yeah, the shit is around no doubt...staying ahead of it will be sheer luck. By the time my plants get it, I'm hoping that you have developed the perfect solution for getting rid of it.
  10. Hey Cloddy, I just found this thread through a guugle search. I talked to a collective of growers in my area this fall, and it reaked widespread havoc. The only guys who got by w/o it are the chemical growers it looks like. Both maneb and chlorothalonil will totally prevent it, but they are definitely not organic. Next year I may do a few early treatments with Maneb, and then switch over to organic solutions later. I'd rather use a manganese based fungicide than copper any day.
  11. Weird. We just talked about this in another thread. I got it on my tomatoes this year but it never spread to my weed. I bought the 3 in 1 fungicide from garden safe and it knocked it out in 3 weeks.
  12. Yeah, I was trying to find photos to compare what happened to mine this year and found this older thread. It looks like it's way more widespread than just the S.E.It's been shitty here this year, and if anyone still has some late ones in the woods I bet they are screwed.
  13. Well one of my girls on my side of town ended up getting blight this year. slowly killed her off. I went on vacation and had a friend watch over her and when I came back she was completely yellow and dead. My other two girls were clones and I have used synthetics on them all year and they're doing great. I'm a little farther north though, like a lot farther north. About to Canada so that might have something to do with it not being so bad here.

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