Early blight in Pa.

manyplews · July 22, 2013

7/22/2013
After a wet,humid June in SW Pa. and 90 degees and 90 % humidity this last week,my tomatoes are showing some symptoms of disease.
I've sprayed every week with Daconil whenever there appeared to be a chance of a 24 hour window with no rain.
I also mulched with newspaper and rye straw.

Beth Krueger Gugino, PhD
Assistant Professor – Vegetable Pathology

at Penn State,has confirmed that this is early blight.

Ron

bcday · July 22, 2013

Why do you need a 24 hour window with no rain? Daconil doesn't take 24 hours to dry.

Early Blight and other foliar fungal diseases such as Late Blight and Septoria need damp conditions to germinate and grow. The protective coating of Daconil needs to be in place *before* it rains, because under favorable conditions the spores can germinate on an unprotected leaf long before the rain stops. Sprays such as Daconil are formulated with spreader/stickers so that they will protect the foliage for some length of time during wet weather. They don't wash off easily. You can actually see water droplets bead up on a Daconil-coated leaf the same as they do on a well-waxed car finish.

Eventually the coating of Daconil will degrade, so you do have to renew it and might need to renew it more often if you have a lot of wet weather, but you don't need to wait for 24 hours of dry weather.
***

"Alternaria spores germinate within 2 hours over a wide range of temperatures but at 80 to 85ºF may only take 1/2 hour. Another 3 to 12 hours are required for the fungus to penetrate the plant depending on temperature." -- http://umaine.edu/ipm/ipddl/publications/5087e/

"In the presence of free moisture and at an optimum of 28-30°C (82-86°F), conidia will germinate in approximately 40 min. Desiccated germ tubes are able to renew growth when re-wetted, and, hence, infection can occur under conditions of alternating wet and dry periods." -- http://www.apsnet.org/edcenter/intro...atoTomato.aspx

manyplews · July 22, 2013

http://www.greencast.co.uk/media/105...%20tu_2009.pdf

"

The high quality Syngenta
DACONIL WEATHER STIK
formulation ensures
protection sticks and stays in
wet conditions, when other
chlorothalonil products can
have washed away"

You may be right,but I feel better if it has 24 hours to dry and "kick-back".

For the month of June and the first 10 days of July,it seemed like it rained at least every other day and the humidity was over 80% all the time.Ideal conditions for blight!

kevn357 · July 24, 2013

Early blight is always a problem in many areas, but it is not late blight...Confirming that early blight is around is like saying i have garden.

July 22, 2013	#1
manyplews Tomatovillian™ Join Date: Jul 2013 Location: SW Pa. Posts: 35	Early blight in Pa. 7/22/2013 After a wet,humid June in SW Pa. and 90 degees and 90 % humidity this last week,my tomatoes are showing some symptoms of disease. I've sprayed every week with Daconil whenever there appeared to be a chance of a 24 hour window with no rain. I also mulched with newspaper and rye straw. Beth Krueger Gugino, PhD Assistant Professor – Vegetable Pathology at Penn State,has confirmed that this is early blight. Ron

July 22, 2013	#2
bcday Tomatovillian™ Join Date: Jan 2006 Location: NY z5 Posts: 1,205	Why do you need a 24 hour window with no rain? Daconil doesn't take 24 hours to dry. Early Blight and other foliar fungal diseases such as Late Blight and Septoria need damp conditions to germinate and grow. The protective coating of Daconil needs to be in place before it rains, because under favorable conditions the spores can germinate on an unprotected leaf long before the rain stops. Sprays such as Daconil are formulated with spreader/stickers so that they will protect the foliage for some length of time during wet weather. They don't wash off easily. You can actually see water droplets bead up on a Daconil-coated leaf the same as they do on a well-waxed car finish. Eventually the coating of Daconil will degrade, so you do have to renew it and might need to renew it more often if you have a lot of wet weather, but you don't need to wait for 24 hours of dry weather. *** "Alternaria spores germinate within 2 hours over a wide range of temperatures but at 80 to 85ºF may only take 1/2 hour. Another 3 to 12 hours are required for the fungus to penetrate the plant depending on temperature." -- http://umaine.edu/ipm/ipddl/publications/5087e/ "In the presence of free moisture and at an optimum of 28-30°C (82-86°F), conidia will germinate in approximately 40 min. Desiccated germ tubes are able to renew growth when re-wetted, and, hence, infection can occur under conditions of alternating wet and dry periods." -- http://www.apsnet.org/edcenter/intro...atoTomato.aspx

July 24, 2013	#4
kevn357 Tomatovillian™ Join Date: Feb 2006 Location: Parma, OH Posts: 147	Early blight is always a problem in many areas, but it is not late blight...Confirming that early blight is around is like saying i have garden.