Late Blight

[PSTeach]

Just read the following on Gant Daily and thought I would share. Be on the lookout.....

 

LOCAL NEWS:

 

 

July 7th, 2009

Gary Abdullah, Penn State University

Serious Disease Threatens Home Gardens, Commercial Fields

UNIVERSITY PARK - The disease that caused the 1840s Irish Potato Famine now threatens Pennsylvania's home-gardening explosion, and a plant-disease expert in Penn State's College of Agricultural Sciences says hobbyists must work with commercial growers to protect the state's tomato and potato crops.

 

The disease Phytophthora infestans is commonly known as "late blight," and it's potentially fatal to all tomato and potato plants grown in home gardens and in commercial fields. Commercial growers know that spraying fungicides can help manage and prevent its spread. But homeowners unaware of this contagious disease may not take timely corrective actions, and their home patches can propagate the disease for miles, according to Beth Gugino, vegetable pathologist in Penn State's Department of Plant Pathology.

 

"Tough economic times have many families taking up vegetable gardening, and tomato is often the most important crop in gardens," Gugino said. "Late blight is a common disease in Pennsylvania and the Northeast since it likes the cool temperatures and frequent rains of our summers. If it gets entrenched in a backyard vegetable patch, it can create a serious problem for neighbors and for commercial growers because the disease spores are easily carried in wind currents to infect susceptible plants in even the most remote areas in our region."

 

This year's battle with late blight is further complicated by other factors: a moist spring has brought the disease at the earliest it's been reported over such a broad region of the country. And a tragic mistake has large retail stores from Ohio to Maine unwittingly selling blight-infected plants.

 

"Last season in Pennsylvania, there was only one report of late blight on tomato and two on potatoes, and those developed later in the season," Gugino said. "And never before has such an extensive distribution of infected plants occurred. The exceptionally contagious spores can spread from plant to tomato plant on garden center shelves, and late blight has been confirmed on tomato plants in home and garden centers in several counties in the state -- and the number is increasing daily.

 

"State Agriculture Department inspectors currently are visiting 'big box' garden centers across Pennsylvania and other affected states, working with the original supplier to remove and destroy any infected plants on store shelves."

 

By the start of July, late blight on tomato and/or potato plants from home gardens and in commercial fields has been confirmed in Bedford, Blair, Centre, Washington and Lancaster counties, and more reports are expected. Outbreaks also have been confirmed in states as far south as South Carolina, and north to Montreal and Quebec. Petunias also can be infected by late blight and show similar symptoms.

 

"Given this scenario, we must assume that many infected tomato plants have been planted across the entire region, if they originated from so called 'big-box' stores," Gugino said. "In Pennsylvania, several cases of infected plants in home gardens have been traced back to these stores."

 

While it's a problem for home hobbyists, she explained, the bigger threat is to commercial growers. Under the right conditions, blight spores thriving in backyard gardens can infect entire fields of tomatoes and potatoes several miles away. So, what starts as a minor disappointment for amateur gardeners can turn into a huge expense for commercial growers in the region.

 

"Growers have access to several very effective fungicides, so if they monitor their fields regularly and maintain a fungicide program, we hope they will be able to harvest a crop," Gugino said. "But identifying and reducing the sources of inoculums is key. We are collecting isolates of the pathogen from each

confirmed sample that comes to us, so that they can be genotyped. This will help identify where the inoculum is coming from."

 

The lesions that develop on tomato leaves, stems and fruit are very obvious to the naked eye. The edge of the water-soaked lesion, on either the top or bottom of the leaf surface, will be covered with white fungal growth that contains the spores. On the stems, late blight lesions appear brown to almost black. The same lesions also will develop on the fruit, either directly on the infected plant, or after a few days sitting on your kitchen counter.

 

"Lesions are not a danger to humans, so most of the fruit can be used if the affected area is removed," she said. "The good news is that the late blight pathogen is not seedborne in tomato, so tomato plants started from seed locally are most likely to be free of the disease, at least for now."

 

Gugino urges gardeners to inspect their tomato plants daily, and to take quick, decisive action when they see symptoms.

 

"Any plants with symptoms should be removed, placed in a sealed plastic bag and left in the sun for several hours to kill the spores before disposing of them in the garbage," she said. "Don

[Petee]

Ugh, we'r all going to starve to death or die from chemicals!

[lavender]

That about nails it! The plants that started it in my neighbor's garden were from a "big box store". It spread from them to her original plants which came from other sources. Fortunately she is out in the woods. I'll pass this on to her.

The fungicide that I have is cholorothalonil which is mentioned in the article. If anyone is interested it is put out by Ortho under the label Garden Disease Control with a stipulation that is was formally Daconil, a registered trademark.

Thanks, whoever. I think I wll put this in our newsletter and up on our website. It is very worrysome. Perhaps you should post it in the main forum.

[Petee]

It's even more reason to buy from local growers!  Those backyard plants can be nicer and your money goes back to the community!

[Smokefree]

I am a member of the yahoo group tomatomania and there is a wealth of information there. Many gardeners are having problems with their tomatoes this year. You can learn a lot from that group and it is very interesting. They are a very friendly group from all over the US.

[Petee]

Well, one tomato plant bit the dust and another has spots.  And yes, they both came from stores.  I should have stuck to the ones I grew!

[Smokefree]

That about nails it! The plants that started it in my neighbor's garden were from a "big box store". It spread from them to her original plants which came from other sources. Fortunately she is out in the woods. I'll pass this on to her.

The fungicide that I have is cholorothalonil which is mentioned in the article. If anyone is interested it is put out by Ortho under the label Garden Disease Control with a stipulation that is was formally Daconil, a registered trademark.

Thanks, whoever. I think I wll put this in our newsletter and up on our website. It is very worrysome. Perhaps you should post it in the main forum.

Would this also work for other problems like bacterial spot? That is what I think mine have.

[lavender]

The active ingredient in Daconil is a fungicide and will not work on bacterial diseases. Some kinds of tomatoes are more resistant than others to these bacterial diseases and generally it is advised to plant those if you have a problem.  The treatment is here: http://www.ag.ndsu.edu/pubs/plantsci/hortcrop/pp736w.htm#control  The treatment doesn't sound as though it could be obtained for home use. I have never heard of streptomycin sprays although you might find something with copper in it. Remember that it is the copper and not the fungicide that is the goal so it doesn't matter what the spray is as long as it contains copper. Daconil may indeed contain copper as fungicides sometimes do but the inactive ingredients are not listed on the bottle. The Ortho website is here http://www.scotts.com/smg/brand/ortho/orthoLanding.jsp?branPage=ortho&campaign=rdorthodotcom  Perhaps they can help.

[geezerwriter]

For those who want a hard copy, the same story was in Friday's Courier-Express, Pages 2-3.

[Petee]

Yes, the Courier did a great story on it.  I cut it out.  Thanksm Dubed!

[mosha]

Haven't seen the article, but have used Bonide's Fire Blight Spray on fruit trees.  It contains 21.2% streptomycin sulfate and is labeled for fruit, flowers and shrubs (not specifically vegetables).  This product is available at most farmfeed/nursery stores but might be hard to find at non-specialty outlets.  

[lavender]

Haven't seen the article, but have used Bondie's Fire Blight Spray on fruit trees.  It contains 21.2% streptomycin sulfate and is labeled for fruit, flowers and shrubs (not specifically vegetables).  This product is available at most farm feed/nursery stores but might be hard to find at non-specialty outlets.  

That would work on smokerfree's bacterial spot but not on the late blight. Nice to know it is out there.

Of the plants I sprayed with the recommended fungicide with cholorothalonil aka Daconil only one is still alive. They were so far gone that it is probably surprising that even one made it.

One of the growers that I spoke to at the Farmer's Market on Saturday says that the spores can last in the soil for 7 years. I think this is just the ones that encapsulate. (There are 2 kinds.) The other kind live only in the plant material and can overwinter that way. That is why it is so important to properly dispose of the diseased plants.

Thanks to the Courier for getting the word out. We don't want our tomato growing messed up for years to come. What's a garden without tomatoes?

[Smokefree]

I am not sure what my plant's problem was but they all had it. Now I have it solved. Between taking off the affected leaves daily and spraying with first one product and then Daconil they are all healthy looking now (minus quite a few lower leaves LOL) and covered with blossoms and green tomatoes. I had to go to three stores to find Daconil and I got the last bottle. I had them check and they have more on back order. I think a lot of people are having problems with tomatoes this year everywhere from what I have read. Many people have lost all their tomato plants and I really feel for them. I never saw whiteflies before yesterday at a local store. I know it's whiteflies from the descriptions that I have read. A plant was on the clearance shelf and when I moved it to look at it swarms of those things flew out looking like dust at first.

[lavender]

Yeah, I've got them this year too. They swarmed off either the butterfly bushes or the rhubarb yesterday? And I saw them in the greenhouse too. What are you using on them?

Glad your tomatoes cleared up. Mine are still clear but I've made up another batch of Daconil for another blighted friend.

[Smokefree]

I don't have the whiteflies on my plants. I just saw them on the clearance plants at the store yesterday. I hope we all get through this season with lots of tomatoes. LOL

[Petee]

I still have about 30 tomato plants of varying sizes, some with tomatoes on them.  Some are free and others are a donation because of where they came from.  If you have lost your tomatoes then a couple of these, well fed and watered will still give you some good table tomatoes!  E-mail me at cshenkle@verizon.net or call 371-3322.