Monday, July 18, 2011

Info on the Dreaded Wilts

I started to respond in the comment section to several questions from Barefeet in the Kitchen and then decided my response was getting a bit long-winded for that venue.

I should qualify this advice by admitting that we are not experts in this area but have done a LOT of research and asked a lot of questions....and would welcome any contribution from gardeners who have had experience with these diseases.

We've examined our plants and have determined that the probably cause is one of the Wilts, Fusarium or Verticillium. These fungus were probably in the soil for some time but have been 'triggered' into action by the wet spring. They are similar to the fungus that causes 'damping off' and some of the same preventative measures apply. Unfortunately, sterilizing an entire gardens worth of soil is not feasible so we are choosing to do the following...

2. Pulled out the plants that were near death and those should not be thrown in the compost pile because the fungus can survive unless subjected to intense heat. (Which means it might die in the valley but you'd be taking a chance.)We chose to leave
a lot of the plants in the ground in the hope of harvesting the tomatoes, especially in the beds where they all looked sick anyway.

3. Next year, plant resistant varieties or ones that have shown resistance this year. One of the heirlooms, Chico, looks lush and healthy despite being in a bed where even the Early Girls are suffering.

Here are some helpful excerpts from our Web searches ~

Fusarium wilt and Fusarium crown rot symptoms begin as yellowing of older leaves. With Fusarium crown rot, the leaves often turn brown or black and eventually wilt. With Fusarium wilt, the yellow leaves turn downward and droop.Fusarium oxysporum, the cause of both diseases, is a common tomato fungus that lives in the plant's vascular system, which carries water from the roots to the leaves. To see if either of these diseases is present:

  • Check watering practices. Both over- and underwatering can mimic disease symptoms.
  • Check the roots. Discolored roots indicate root rot.
  • Cut the lower or main stem and look inside at the vascular tissue. Fusarium wilt causes a dark brown discoloration within the vascular tissue. Fusarium crown rot causes a rot or canker at the base of the stem and possibly a root rot. (We found when we cut open the stems of infected plants the entire diameter was brown.)

Most tomato seeds or transplants are labeled with a code such as "VFN," "VFNA," "VFNT," etc. This indicates that the plants are resistant to Verticillium wilt (V), Fusarium wilt (F), southern root-knot nematode (N), early blight (A), or tobacco (tomato) mosaic virus (T). Do not plant tomatoes, potatoes or eggplant in the affected area for two or three years.

And on another site~

The first line of defense against wilt is to use disease-free seedlings. This avoids introducing wilt fungi into the garden. Remove and destroy wilted plants and all debris of tomato and other susceptible crops at the end of the growing season. Rotate tomato-growing areas, growing tomatoes in the same part of the garden only once in four years. The benefit of rotation is less with wilts than with other diseases since both wilt fungi survive for years in the soil and the Verticillium fungus attacks many different crops. Fungicides for control of leaf blights have no effect on the wilt diseases, which are internal infections. Once soil is infested and further rotation impossible, the only possible management practice is use of resistant varieties.


Barefeet In The Kitchen said...

Thank you so very much for all of this information. Our compost is already trashed for the year, since we had no idea not to throw our squash in there after it developed powdery mildew. :(

It sounds like we're very lucky to only have this on two of the 10 tomato plants. One of them is right next to our sunburst cherry tomatoes and they are the best producing ones out there. Weird.

I'm going to read some more today and then figure out what we are doing. Thank you again for all of this information!!!

Maureen said...

You are welcome...tho I'm sorry you're experiencing the same kind of problem. I do have to confess, the 'should not' go into the compost pile was in reference to what is proper, not what we actually did....sigh. I read that part AFTER we'd already thrown the infected plants into the pile. Now we're just hoping we can heat the compost up enough to kill the fungus (going to put some fresh manure in there and wait for 100+ temps:)

Please come back and share if you find any more info...we can all benefit from knowledge about these things....thanks!

What if it's today? - A survivalist's blog said...

Sorry to read about your blight. With all the tomato pictures that you posted in April I was waiting to hear about your bountiful harvest. I wonder if it was because the plants were put in early? Our plants didn't get in until the end of May and we haven't had any of those issues.

With all the hype about heirlooms, your experience has taught me that this is one reason to have a combination of heirloom and modern varieties.

Maureen said...

Could be the early planting...seems fitting since we're usually LATE and we were thrilled to have gotten them in so early....sigh.

I have to agree with you on the heirlooms. Tho we do love trying new shapes, sizes and colors of tomatoes, we'll be planting them a bit more judiciously in the future.