Nematodes...again

[Quiet Storm]

Has anyone used diazinon to control nematodes on hostas? If so, what were the results? I was cleaning the storage area under my porch today, and found a bag of granular diazinon that my husband bought years ago to treat our lawn, as well as a small bottle of liquid diazinon. The homemade insecticidal soap and disulfoton have helped, but the nems are still spreading. I may try the diazinon in the worst affected beds. With the granular diazinon, do I just sprinkle it on the soil around the plants and water it in, or do I need to work it into the soil? Should I treat the beds now, or wait until spring?

I've had great success with the hot water bath treatment for nems (have only overcooked one), but some of the plants now affected are my larger specimens, including Sum and Substance and Lady Isobel Barnet, and heat treatment is not really a viable option for those.

[Chris_W]

Hi Gloria,

In studies Diazinon was shown to kill something like 60% of adult nematodes, but doesn't do anything to eggs, and since it is mostly a contact spray I don't think the effects last very long, so you would have to do repeated sprays. I bet if you were to alternate Diazinon with other insecticides as an overall spray program it would help a little.

And yes, you can just water in the granules.

I would wait until spring. You won't get rid of the nematodes completely with it, but if you use it next season you might reduce next summer's damage.

Good luck with the battle!

Chris

[Quiet Storm]

Thanks Chris.

I will begin using the diazinon in the spring, in combination with the insecticidal soap and disulfuton. Have you ever used Vydate? I have a small vial of it that I have been avoiding using. I was told to use a half teaspoon per quart of water to treat nem infested hostas. Is it better to use that in the spring as well? Or not to use it at all?

Another problem I am having is the sudden browning of the leaves on some of my hostas. The browning starts at the tips of the leaves and spreads downwards to the stems. I haven't looked at the crowns of the affected plants yet, so I don't know if there is any evidence of rot there. Does this sound like a fungus? If so, what fungicides have people had success with? Is it too late in the season to use the Bayer all in one flower care product that was mentioned in another post in this forum?

Thanks.

Gloria

[eastwood2007]

Hi, Gloria -

Sorry you are having so much trouble with these nematodes. The question you asked about whether it is too late to use the Bayer all-in-one....it does have fertilizer in it. Bayer also makes a Disease Control forumula that has the same fungicide/insecticide in it without fertilizer. I found it both at Lowe's and Home Depot. It was also at some of the better garden centers here, but more expensive. The garden centers may carry it all year round, whereas L's and HD may not...

[Quiet Storm]

Thanks Charla. That's what I was concerned about -- the fertilizer in the Bayer all in one. I will try to find it without the fertilizer. We had such a wet August in eastern MA, that nematodes, slugs, and fungi have all gotten out of control in my hosta beds, and I'd like to try to get the upper hand again (if such a thing is possible).

Gloria