Tuesday, October 13, 2009

Late blight in tomatoes and potatoes in 2009

The first report in Michigan of potato late blight caused by Phytophthora infestans was on potatoes in southwest Michigan. The Kirk Lab at MSU confirmed the disease on tomatoes from home gardens in Lansing, East Lansing, Sturgis, Traverse City and Cass City in the following few days. Reports of late blight on tomatoes and potatoes in Montcalm and Mecosta Counties quickly followed and it was clear that an epidemic had broken out in many areas in Michigan. Home gardeners, organic and small growers were particularly badly affected. In 2009, an uncommon strain appeared on both tomatoes and potatoes. The strain is similar to US-14 (the established strain in most of the US is US-8). The disease is normally managed by preventing survival of its over-wintering stages in potato tubers by crop management and waste potato management and use of herbicides in rotational crops followed by regular applications of fungicides. Such management restricts epidemic development and usually excludes the disease from urban and rural areas.

At Michigan State University the Department of Plant Pathology runs a website that addresses the risk of this disease and describes measures for controlling initial sources of the pathogen and for controlling the disease should it appear during the season (www.lateblight.org). Late blight has caused considerable loss to growers in areas where the disease is uncommon, and to home gardeners. In Michigan, damage to tomatoes increased as the season progressed and put commercial potato producers at increased risk resulting in an increase in the application of crop protection products. Base-maintenance for potato late blight control for commercial growers would normally be about $100/A/season, but in 2009 this cost rose by about 50% due to increased frequency of applications and more use of expensive late blight containment fungicides. This is effectively an increase of about $2 million. In addition, growers have to protect tubers going into long-term storage with disinfectant-type products.

Whatever the source of the disease, at MSU we are developing educational programs for growers to help them manage this disease in both tomatoes and potatoes. Growers may be asking "Did I do something wrong and what can I learn from this to become a better manager/grower?" Fungicides are available but that does little to help organic tomato and potato producers as they have very little other than cultivar resistance to rely on, and little is know about this resistance with this new strain of late blight.

During August an educational pamphlet was developed in conjunction with the Michigan Potato Industry Commission and distributed by MSU extension and Bedford Farm Supply Services to Amish growers throughout mid-western Michigan who were severely affected by the disease. The pamphlet and further information can be found at your local MSU extension office orat the Michigan Potato Diseases website (www.potatodiseases.org).


Thursday, August 27, 2009

APS 2009 Posters now available on-line

The posters presented by the lab at this years American Phytopathological Society Annual Meeting in Portland, OR, are now available for download on the recent publications webpage. This year we presented four posters at the meeting along with several oral presentations.

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Saturday, August 22, 2009

Late blight on tomatoes

Check out the video below showing the devastation caused by late blight on tomatoes in west Michigan.


Saturday, August 01, 2009

More discoveries of Late Blight in tomatoes

Late blight has now been found in a further 2 locations, the Greater Lansing area (Ingham county) and Lapeer (Lapeer county). Please note that in both these locations late blight was found on tomatoes. Late blight has not been found on potatoes in either of these locations.

Thursday, July 30, 2009

Late Blight found on Tomato in Gratiot county

Today (July 29, 2009) the plant disease diagnostic center at MSU received a tomato plant that had late blight on both the fruit and foliage. This sample was from a home gardener in Gratiot county. There has been a severe outbreak of late blight on tomatoes in the Northeast, in states including New York. Potato growers in Gratiot county should be on alert as in the Hudson Valley region of New York, the disease has jumped from tomatoes to potatoes and is wreaking havoc in both. The source of the outbreak in the Northeast is being investigated by pathologists and it is thought that home gardens likely helped spread the infection: Lowe's, Home Depot, Kmart and Wal-Mart all sold tomato seedlings with late blight in their garden centers from April to June. As such this find in Gratiot county may also be from a similar source. The New York Times has published several articles on the subject. Click here and here for more information.

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Tuesday, July 28, 2009

Late blight discovered in SW Michigan

A late blight outbreak was reported and has been confirmed in St. Joseph county. So far a single outbreak has been confirmed in a field near Sturgis. With the thunder storms and heavy rains that have swept across the state in recent days it is important to be extra vigilant when scouting fields for late blight. Particular attention should be paid to pivot tracks and other such lanes created by farm machinery. For further information on measures that should be taken when late blight is observed refer to the Late Blight extension bulletin. This bulletin is also available as a high quality downloadable .pdf file.

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Wednesday, May 20, 2009

New Publications for 2009

Two new research publications are now available for download on the website. The first publication deals with the impact of different US genotypes of Phytophthora infestans on potato seed tuber rot and plant emergence in a range of cultivars and advanced breeding lines. The second publication discusses recent advances in screening potato cultivars for increased tolerance to common scab (Streptomyces scabies).

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