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Connecticut

It seems this year with all the rain especially in the Northeast pumpkin growers have had many challenges.

What I am wondering is if you have seen your leaves burn up or melt-down in 24-hr (or less)? The stalks remain heathy in appearance but the leaves are dead. Usually it starts at the base and spreads along the main vine.

I have determined that this disease is Phytophthora.

The four questions for you to answer, (short answers encouraged)...

1.) Have you seen this disease?
2.) What year did you see it?
3.) How fast was your pumpkin growing?
4.) Your method of action to try and prevent the spread?

I am trying to determine the occurrence of this disease in our Giant Pumpkin patches, and I appreciate any input.

Thank you for your help.

-Matt

8/18/2008 9:06:03 PM

Wi

Matt, if you in fact have a root rot disease (Phytophthora), there isn't much you can do. Preventative programs are really the only way to go. Once the roots are rotted there is no way to "unrot" them. The only action you can probably take at this point is to preventative spray your healthy plants and get the diseased ones out of the patch ASAP.

Subdue / Aliette are 2 good fungicides for root rot, but you need to know for a FACT what you are dealing with before you start spraying. Diagnosis without a lab is impossible.

Best of luck to you.

8/18/2008 11:10:09 PM

Connecticut

Hi Chris S.

Thanks for the information. I agree once you get it, control is difficult. However it seems that if you catch it early and aggressively remove the infected part of the plant you can suppress the spread. (Or at least this is what I have seen this year.)

I am interested to know if this is wide spread disease because I have not really seen this before and there are some large scale farms experiencing this problem also. So could it be ideal conditions for development or is this becoming the next major pumpkin disease?

I have my own ideas and I am interested to hear what others think.

Thanks again for your reply.

8/19/2008 10:42:31 PM

Wi

There are 3 of us here in WI within a short distance that all have phthium. 2 of us have soil from the same source the 3rd does not. Though we are still researching / learning once you have a root rot pathogen in the soil it is VERY difficult to deal with down the road. Pythium spores can live for over 40 years in the soil

8/20/2008 9:24:19 AM

Ctpumpkin@optonline.net

I've dealing with Phytophthora in Rhododendrons for years. Like Chris said, Banol, Aliette, etc will all work if it's caught very early (IE before the symptoms are even visible to the untrained observer). However prevention is the only effective way of managing Phyto in a year like this one has been.

Now that Aliette is off-patent we can afford to treat susceptible crops to Agri-Fos fungicide.

I just had the US bottler (friend of mine) send some to SeedOutlet.com so growers here now have a cost effective treatment option.

Agri-Fos is labeled for Pumpkins (unlike Aliette) & other edible vegetables. It can be applied as a foliar, drench & preplant soil treatment. Cool stuff.

8/20/2008 4:43:57 PM

Pembroke, New Hampshire

I've got it this year, eating away at my plants. I've lost one plant to it, and 20% of another. I'm trying to cull all the bad leaves to slow it down, and spraying copper soap (I don't know that it will help with the phytophophthora, but will help the plants resist other diseases). I have one plant still not affected and I'm trying to practice patch hygeine to prevent it's spread. The dryer weather is helping as well.
I've been told a soil drench of Ridomil next spring (twice, 4 weeks apart) will help suppress it as well. I havn't been able to find it yet- might be restricted.
I've also been told that a "smear layer" can develope in the soil, below the depth which is rototilled, which forms an impermeable layer and restricts soil drainage. I've been told to do a deep cultivation of the soil...if I can find someone with the right equipment who's willing to risk the spores.
Otherwise, let the soil go fallow for 3 years, or scrape it all off and replace it with new soil.

8/20/2008 6:36:00 PM

hamilton,Ontario

can someone take a look at my diary and see if this is what I got?????????

8/20/2008 7:19:54 PM

Wi

cndadoc, IF you have a root disease removing leaves will do nothing. The roots are diseased not the leaves. The leaves are discolored because of lack of nutrients.

Subsoiling is a great idea IMO and we'll be doing it here. You can borrow someone elses, just be sure to sanitize the equipment before you bring it back.

In my experience once every 4 weeks for treatment is NOT enough. I tried that here this year and still lost 50% of my plants. We'll be on a 14 day interval next year if we don't replace our soil. Still undecided.

8/21/2008 9:12:37 AM

Pembroke, New Hampshire

Chris S.
Have you used Ridomil? Where can it be purchased?
Understood about the root/leaf conection, but just trying to keep the remaining plant healthy by cleaning debris. Lost another 6 leaves today...they just wilt up and die. I'm just about ready to pull the whole plant, but the pumpkin is still putting on 10 pounds a day (but dropping).

8/21/2008 5:27:08 PM

Connecticut

Eng6900-

I took a look at your pictures and to me it looks like you may have Downy Mildew. This can be quick acting but is a leaf disease and not a soil based one. The products mentioned above have some effectiveness on Downy, but they must be applied soon.

However, spray damage is another possibility, so do these symptoms occur where you tend to spray? (Or spray extra heavy.) Are you noticing leaves that are wilting or just these yellow spots?

8/21/2008 5:35:50 PM

Wi

I have not used Ridomil. Only Aliette and Agri-Fos. Probably incorporate some Subdue next season.

8/21/2008 6:02:16 PM