New strain of Goss's wilt on maize suspected

Crop scientists are asking farmers for help. They know plants were attacked by a bacterial disease called Goss's leaf blight and wilt. But University of Minnesota's (MSU) Dean Malvick wants farmers to send diseased leaves.

Goss's can reduce ear size, or at its worst, kill the plant completely. The disease has a long history in the U.S., but it remained fairly isolated for decades until recently. Malvick wants to know whether the bacteria affecting Minnesota fields are the same as the ones wilting corn across the Midwest, or whether they are some sort of variant.

The disease was first confirmed in Minnesota in 2009 in 2 fields. Last year [2010], there were maybe 40 fields infected. Reports of the disease have increased "dramatically" this year [2011] in the state.

Malvick said he doesn't have a final tally for 2011, but the area affected will be much higher than in 2010.

He said researchers don't know why Goss's is increasing so fast. Its rapid increase over the last few years is something researchers are concerned about.

Goss's wilt and blight of maize is caused by the bacterium Clavibacter michiganensis_ subsp.  nebraskensis. It is a persistent and economically serious disease of susceptible maize hybrids in several states of the USA. In 2009, it was reported for the 1st time outside the U.S., from Canada.

The bacterium can also affect some grasses, which may serve as pathogen reservoirs. Symptoms include systemic wilting of plants and/or leaf lesions and blighting. Infection of leaves, stems and roots occurs primarily through wounds (mechanical, hail, or insect damage), and plants are susceptible at all growth stages.

The pathogen is seed transmitted and overwinters on crop debris and maize kernels. Disease management includes cultural practices to minimise inoculum, crop rotation, and use of resistant crop varieties.

Other subspecies of C. michiganensis affecting different hosts are found elsewhere, including sepedonicus (potato ring rot) and michiganensis (bacterial canker of tomatoes), which can cause severe yield losses on their respective hosts.

Comments (3) Leave a comment 

To Dr Malvick.
There seems to be a variance of opinion on the number of races of Goss' Wilt. Some in Illinois and eastern states believe there is only one race. University of NE disease specialists believe there are ten to an unlimited number of races. Most extension personnel and agronomists are only looking for leaf dieback of the leaves in the upper canopy. It appears that much of the disease moves from the ground up and got established in the moist area behind the V4 or V5 leaf sheath where the dew collected during the very dry and hot July. This blackish to carmel colored mottling is not mentioned in the literature.
Most growers still are not recognizing the fact that their fields were affected. This Ostrich approach won't cut it in 2012 in the quest to minimize the disease's effects and cost to the bottom line. There will be yield checks taken shortly from several nutritional products that were applied in 2011. The fields seem to show that the advance of the disease was halted and symptomology disappeared.

We have viewed this disease in area corn fields for many years. We feel strongly that to date Goss's wilt is seldom is seen in Organic productions fields. A question to consider: is the genetic base of the GMO's corn's showing this problem? Yes I believe thi/s to be true. . We are into hundreds of fields yearly, see Goss's wilt in conventional fields. Noted that it is here in Nebraska and getting more acres yearly it appears from our walking fields and taking notes on growth all season long. Good independent agronomist report all they find, they do not cover up problems. The agronomist who are selling seed and chemicals and have to cover the problems with the seed they sell does happen far too often.

Have friends in NE colorado which been dealing w/ goss's for 15 years or more now. They think have different races. Hybrids they use to get good resistance/toleranence no long work very well. The seed companies so no it enviromental stress but consult on tens thousand of acres been seeing this for several years now.