sunflower problems

I’m having some problems with my sunflowers. First two of them turned black and began to die. I removed them from the garden to prevent further spread of what ever it was. Does anyone know what it was (the flower buds turned black then the leaves started to turn black and wither)? The next problem I am having with sunflowers is that there are a lot of holes in the leaves and there are yellow spots all over them. I was hoping to grow them out for seed but it’s not looking too good.

[Cyngbaeld]

Don't know where you are. My first thought would be too much water. And my second thought is that they got frosted. Sounds like they are rotting where they stand, which means they are dead.

[debitaber]

I tend to agree, to much water, and I think that they might have been frosted. however, the holes in the leaves could be the work of a beatle.
What part of the country are you in? We had two frosts here where I live last week. [mich]. And it got my apricots, they now are black, and shriveled up, they look like almonds, that have been dried up. IT also got my red repberries. and the leaves, are now shriveled up, and dead, but new leaves are coming, just lost my berries.
I didn't have the heart to check my other fruit trees. just couldn't do it. But I figure it probably got most.
The garden is protected,so the frost didn't get the garden, but the plants just aren't blooming like they should be.
been a mighty funny year for the weather. :waa:

Well it's not frost, I'm in south Florida (vary hot here and has been for a while). We did have rain every afternoon for about a week but only a few of the sunflowers turned black. The others bloomed but the leaves are in bad shape

[Cyngbaeld]

Are the dead ones in an area where the water pools? Or are you in a real sandy area (good drainage)? Cause it sure sounds like too much water has caused the roots to rot.

Vary sandy area on a slope. The stems and leaves where fine. When the flowers were ready to bud the flowers turned black. I though uh oh. Two days latter the leaves started turning black, so I cut them down. Oddly the ones that turned black were the strongest tallest growing, thickest stemmed of the bunch. :s The ones that remain show no signs of what ever happened to the ones I removed. Yet they have there own problems. Like I said, lots of holes in the leaves and yellow spots. They are still alive but are showing many signs of stress most likely due to the extreme heat. But what ever the yellow spots are is contributing. A neighbor of mine is growing sunflowers as well but dusts them with poison. His leaves look fine but are still showing signs of stress due to heat.

[Cyngbaeld]

Your neighbor may just be delaying the inevitable with his poison. Bugs tend to attack stressed/unhealthy vegetation and leave healthy stuff alone.

You may be able to save some of your plants by adding a well balanced fertilizer. My thinking on this is that the rain may have washed away soil nutrients. sand does not hold on to nutrients very well. The bigger plants may have sucked up their nutrients and crashed. That is the princeple behind 'weed and feed', it makes the weeds outgrow their supply of nutrients, then they die. Frankly, I'd just pull the remaining plants and work some organic material into the soil and let it rest until you are ready to plant a fall garden. Or plant a cover crop for green manure in that spot. Usually when a plant becomes so unthrifty as these seem to be it is not worthwhile to try to hang on to them.

If you would like to try it, there is an active Florida garden forum at www.gardenweb.com they could prob give you more specific help. (Not trying to pass you off or anything, but they are in your area and might know more than I do about Fla conditions. I've mostly grown sunflowers in the desert, tho I've gardened elsewhere.)

[suelandress]

http://www.fargo.ars.usda.gov/sun/sundisfd.htm

Try that.

Thanks suelandress,

That explains it. Sclerotinia head rot looks very similar to what happened to the black ones. Sunflower mosaic virus looks similar to what is on the leaves of the leftover flowers. I did find two blackish beetle like bugs eating the seed in one of the flowers and got rid of them. I also saw a striped (orange and black) cucumber beetle on them yesterday (I think). They have started to form seeds so I hope they make it to full maturity with out the bugs/birds eating all the seed. Thank you everyone for the advice and information. I do plan to plant a cover crop for green manure after this. What would you suggest? I would hope to plant summer alfalfa but am not sure how it will do down here in south Florida. If summer alfalfa will grow well down here, then I can feed some of it to my rabbit and work the rest into the soil. I will follow with corn, sunflowers, and jurusemlem artichokes most likely.