Blight

Here we are in the midst of summer. Perfect for picnics, all sorts of outside activities, and enjoying the freedom this season brings. We will be celebrating Independence Day and the weather forecast is great. The summer, so far, has been much better than last. Remember? Lots of rain, lower than average temperatures, and a disappointing growing season for the home gardener. Even worse, this time last year, we were plagued by late blight. While weather does play a part in the development of the disease, the pathogen, Phytophtora infestans, has to be present in order for late blight to develop.

In parts of Pennsylvania there have been confirmed cases of late blight. Late blight is a disease that can kill plants and wipe out crops in a few days if conditions favor disease growth. Those conditions described the 2009 growing season – cool to moderate temperatures with wet weather. Once you have seen late blight wipe out a garden or field, you begin to understand how important preventative measures are to protecting your home garden.

Late blight affects primarily potatoes and tomatoes, not other garden crops. Spores can blow for many miles, land on a wet tomato or potato leaf and start a new infection. So the disease can quickly spread from one garden to another. Infections can be prevented by regular spraying with fungicides containing chlorothalonil or mancozeb, but applications must begin before the disease gets started and continue through the growing season every 7 days to protect new growth. If weather is dry, you can stretch this interval; but if we have heavy rains, you may have to shorten it.

Gardeners should be spraying fungicides on their tomato and potato plants to prevent infection. Keep in mind that fungicides prevent infection they do not cure it. All plant surfaces should be covered with fungicide before conditions favor infection. Do not wait until after the rain stops to apply fungicides – they should be sprayed and dry before rain starts. Thorough coverage of all plant surfaces is needed for good control.

Remember, fungicides are to be used and handled according to labeled instructions. For more information on late blight, please contact the Penn State Master Gardener Helpline at 570-963-6842 or email: LackawannaMG@psu.edu


Steve Ward
Master Gardener Coordinator
Penn State Cooperative Extension in Lackawanna County
Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce.

Tomatoes, 2010

In just a few weeks it will be time to plant tomatoes. When you buy transplants, choose plants that have a nice green color on the lower leaves. Choose plants with a thick stem. Avoid plants that have blossoms or small fruit unless they were grown in a 6” pot or larger. If you have not added calcium lime for a few years, apply it when you till your soil. Lime will help prevent the tomato fruit from getting blossom end rot. When you transplant tomatoes into the garden, plant them deep. Tomatoes will develop roots from the parts of the stem that are underground. Apply fertilizer soon after planting.

We are concerned about late blight being a problem in tomatoes again this summer. The summer weather will determine if late blight will be a problem in 2010 or not. It has been a problem for growers in Florida again this winter. If we have a cool wet summer, expect late blight to be active. Late blight does not do well when the weather is hot and dry. Fungicides containing chlorothalonil are effective at protecting tomatoes. If you use a fungicide, it will have to be on the foliage before the blight attacks and thorough leaf coverage is critical.

Also, every Saturday, through May 22nd, we are offering a Spring into Gardening Workshop at Bill’s Ace Hardware, Route 435 Daleville, PA. The Master Gardeners will answer your gardening questions from 11 am – 2 pm. Plus, at noon we will have demonstrations on various seasonal topics. This program is free and open to the public. Here are the upcoming topics:

• May 1st - lawn care basics
• May 8th - landscaping for the birds
• May 15th - composting
• May 22nd - home food preservation basics
  
  

For more information contact your local cooperative extension office. In Lackawanna County call 963-6842 and ask for the Garden Helpline or email LackawannaMG@psu.edu


John Esslinger, Extension Educator
Penn State Cooperative Extension
Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce.

Tomato Late Blight: Fall Clean-Up Questions

Can plants with late blight be disposed of by composting?
Theoretically yes, however, plant tissue (including potato tubers) can survive the winter in a warm compost pile. If plant tissue survives, so can the pathogen. Unless you know that you are composting properly, it is recommended that you dispose of infected plants, fruit and tubers in the trash.

Do I need to treat the soil this fall or next spring to prevent late blight from developing next year?
No. Once the tomato plant tissue is dead, the late blight pathogen cannot survive on crop debris. It can, however, survive in potato tubers, so it will be important to destroy any volunteer plants next year.

Can the late blight pathogen survive in or on tomato seed?
No, but there are other pathogens (especially bacterial pathogens) that can survive in or on the seed so there are other reasons to only use seed from healthy plants.

Could the late blight pathogen survive on tomato cages and stakes between seasons?
No. But it is a good idea to disinfect stakes and cages to help control bacterial diseases.

Are there late blight resistant tomato varieties that I should consider planting in the future?
There are some potato varieties with some resistance. These include ‘Elba’, ‘Kennebec’, ‘Allegany’, ‘Sebago’, ‘Rosa’, ‘Defender’, ‘Jacqueline Lee’ and ‘Ozette’. ‘Elba’ is considered the most resistant. There are some new late blight resistant tomato varieties that may be available as soon as 2010.

What can home gardeners and growers do to prevent another late blight epidemic next year?
Make sure that all late blight infected tomato plant and fruit tissue from this season is dead or destroyed. Destroy potato tubers that appear to be infected by late blight and also volunteer potatoes that grow next year.

Next year, make sure to plant healthy disease-free transplants. Examine your plants regularly for symptoms of late blight, especially if conditions are cool and wet. Avoid wet leaves by watering at the base of the plant or by using overhead irrigation during mid-morning so the leaves dry quickly. Improve air circulation by spacing plants farther apart and eliminating weeds.

To see the full article “Tomato Late Blight: Fall Clean-Up” by Beth Gugino, Penn State Plant Pathologist, please visit http://www.ppath.cas.psu.edu/EXTENSION/VEGDIS/Vegetable_Pathology_Home.htm or call your local extension office for a free copy. In Lackawanna County call 963-6842 and ask for the Garden helpline or email LackawannaExt@psu.edu.


Terry Schettini, Extension Educator
Penn State Cooperative Extension in Lackawanna County
Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce

Have You Been 'Blighted'??

It's front page news. It's sad news for home gardeners. It's really bad news for commercial growers.

'It' is Late Blight, which usually starts showing up at the end of the growing season in small patches here and there, started showing up in the beginning of July and it seems like it's everywhere! Below is a link to a PSU article about it but we'd like to hear from you. Have you heard about it this year? Have you been hit by it this year? What's your story? We'd like to know!


Lackawanna County Master Gardeners
Georgiann Eccleston

Late Blight Link