2005 Field observations, news, photos and more (the 2005 archive)

New FL find 8-31-05.  Washington County, FL, has been confirmed positive for soybean rust.  Jim Walker, a Florida Department of Agriculture plant survey specialist, told DTN the Washington County rust detection was in a commercial field in the central part of the Florida Panhandle.  "The infection was light," he said. "The soybeans were in the R-5 to R-6 (full pod) stage. Overall, the rust finds are spotty and the presence of pustules is light."  August was a very busy month for soybean rust in Florida. Fourteen new counties were found to have soybean rust and for the first time commercial fields were found to be infected; one each in Hamilton, Madison, Washington and two in Walton counties. A second commercial field in Washington County was confirmed positive on September 2nd. There are now 22 counties positive for soybean rust in Florida, with a complete bridge across the soybean production areas in the panhandle.  It is recommended that growers continue to monitor for soybean rust. If soybean rust is found, they should consider spraying unless they are at R5 or beyond. As the crop continues to mature and no commercial yield loss has been observed, we do not recommend fungicide application for soybean rust unless the field is positive. Hurricane Katrina brought wind and rain to the Florida panhandle, possibly spreading the rust spores. Disease from these spores may be seen late next week. However, as the crop continued to mature and the typical dry September-October period begins the potoential for economic loss is reduced. Continued scouting during September is critical for later planted soybeans. In commercial fields that are positive we recommend a fungicide application be considered if the field has not yet reached R4. If at R4 or R5 a spray may be warranted, but unless disease is already severe it may not affect yield. In fields without rust, we see this as a "high risk; prior to visible detection"* situation where a fungicide application may be warranted, but less so as the crop matures to R4 and R5. Growers can add fungicides to planned insecticide/boron applications. *see the manual "Using Foliar Fungicides to Manage Soybean Rust" page 26.

New FL find 8-30-05.  Jackson County, FL has been confirmed positive for Asian soybean rust.  The confirmation was done by visual observation (microscopy) by University of Florida pathologists and the find was on soybeans.  Jackson county is in the FL panhandle, between Holmes and Gadsden counties and north of Calhoun county.  There is now a solid line of positive counties in the panhandle of Florida from the Alabama border to Baker county, FL (Baker is negative for the disease at this time).  This latest find makes 21 positive counties in Florida. 

New FL find 8-29-05.  Walton County, FL has been confirmed positive for Asian soybean rust.  The confirmation was done by visual observation by FL Dept of Ag officials and the find was on soybeans from a commercial field.  Walton County is in the FL panhandle, between Okaloosa and Holmes counties, both of which were previously positive for rust this year.  Walton was positive for rust in 2004.  More information on the field conditions in Walton county to follow soon. 

NOTE:  Per Dept of Ag officials, FL will no longer run PCR on every sample; only samples from counties that were not positive for soybean rust in 2004, or new hosts, will be taken through PCR.  All counties which were positive for soybean rust in 2004, and are identified as positive in 2005, will be confirmed by microscopy unless PCR is deemed necessary for other reasons. This change will allow the state to update the USDA map sooner, while still allowing for official confirmation.

New FL Find 8-25-05.  One new county was confirmed positive by microscopy and real-time PCR: Calhoun County.  From Dr. David Wright:  "The Calhoun county plot was in the sentinel plot. The beans were moderate in height and did not have a very high infection level. It was found in one spot."  From Dr. Jim Marois:  "An SBR sample collected in the MG3 in the sentinel plot in Calhoun County yesterday (8/22) was visually confirmed.  This is a first for the county.  It was sent to Gainesville for PCR (Florida is still conducting PCR on all first finds for county observations).  Calhoun County is southwest of Gadsden, which is already red.  On the map it begins to close the gap between the positives in the western –panhandle and mid-panhandle counties.   Close inspection indicated it was just on one plant, but a few leaves had more than 10 lesions."

New FL finds 8-10-05.  Three new counties have been found positive for soybean rust:  Holmes, Okaloosa, and Santa Rosa, all in the FL Panhandle and all bordering GA.  All finds are on soybeans from soybean sentinel plots.  Finds were confirmed by microscopy and PCR.  This brings the number of FL counties positive for Asian soybean rust to 15.

FL finds as of 8-8-05.  Three finds are on kudzu in Alachua, Hamilton and Lee counties. One find is on soybean in Madison County in a commercial field.  All finds were confirmed by microscopy and PCR.  Finds and diagnostics by combined efforts of FDACS/DPI and UF/IFAS personnel.  From Dr. Jim Marois:  "Asian soybean rust from a grower's field in Hamilton County, Florida was confirmed positive with PCR on August 2. This is a new county for Florida, now 9 total, and the first in Florida in a commercial field. The plants are MG5 and over 1.5 m high and very thick canopy. We are finding out more about the find and will report further. For the Escambia County sentinel plot (positive 7/18) the MG3 foci are well developed but still less than 2 m in diameter as of 8/4. Some lesions on nearby MG5 plants. The plot had rain (2 inches Friday 7/29 and 1.5 inches Monday 8/1) since I reported that lesions were not sporulating on 7/25. Lesions were sporulating on Thursday, 8/4. There are now a total of nine counties in FL with positive confirmations of soybean rust: Dade, Hernando, Pasco, Marion, Jefferson, Leon, Gadsden, Escambia, and Hamilton. A suspect sample on kudzu from Hamilton County was collected on July 28th and Alachua Co. on the 29th."

FL find 7-29-05 on Kudzu This find is on kudzu in Hamilton County and has been confirmed by microscopy at the Department of Agriculture.  PCR is being performed by the University of Florida.

FL Find 7-19-05 on Soybean  This find is in a soybean sentinel plot in Escambia County, FL.  This county is the westermost county in the FL panhandle.  The find was confirmed by microscopy and PCR is being run on the sample on 7-19.  The sentinel plot is near production fields and has prompted a change in the management recommendations.  Producers in Escambia County are recommended to consider spraying if their fields are approaching bloom or are blooming.  Producers in nearby counties should be prepared to spray if new finds are in close proximity to their fields and those fields are blooming or are close to blooming.  See the fungicide resources below for information concerning chemicals.

From Jim Marois, UF Plant Pathology:  "Asian soybean rust was visually confirmed July 19 from samples collected July 18 in the sentinel plot in Escambia County, Florida.  (Escambia County is adjacent to Baldwin County, Alabama where there is an infected commercial field and sentinel plot.)  This is a new 2005 county for Florida and the first positive soybean infection in a soybean producing area for Florida.  The infection was found on two MG3 plants and one MG5 leaf that was in direct contact with a MG3 infected plant.  The MG3 plants are at R4 and the 2^nd and 3^rd trifoliates had over 100 lesions.  No other infections were found.  The sentinel plot is adjacent to a soybean field planted about 30 days ago.  PCR will be done this week.  We are recommending that growers in Florida in the western panhandle consider spraying for Asian soybean rust as their plants approach bloom. All soybean fields should continue to be monitored closely for disease development and sprayed if they are found to be positive for Asian soybean rust.

This recommendation is being made now because:

1. recent positive findings on kudzu and soybean in the  panhandle

2. experience with rapid disease increase on soybean in the Marion County sentinel plot

3. the continuing high humidity which favors disease development

4. the approaching bloom stage of our soybean crop

5. and the possible involvement of tropical storms Arlene and Dennis in distributing spores.

We see this as a “high risk – prior to visible detection”* situation where a fungicide application may be warranted.  For Escambia and adjacent Santa Rosa Counties the risk of disease may be higher than for the other counties in the panhandle where soybean rust has not been detected.  However, be reminded that the ‘negative’ panhandle counties have large areas of kudzu that could very well be harboring the pathogen.  *see the manual “Using Foliar Fungicides to Manage Soybean Rust” page 26."

New FL Find 7-6-05 on Kudzu  This find is on kudzu in Gadsden County, FL.  This county is just west of Leon County and just south of Seminole County, GA.  The find was confirmed with microscopy and PCR.

New FL Find 7-1-05 on Soybeans Asian soybean rust has been found near Citra on soybeans at a University of Florida sentinel plot. Detection tests included microscopy, ELISA and PCR.  For more information, click the following link: http://news.ifas.ufl.edu/story.php?id=421.   From Jim Walker, DPI:  "Jim Marois (UF, Plant Pathology), David Wright (UF, Agronomy) and I surveyed the positive sentinel site in Marion County, FL, and we thought the following information would be helpful to all concerned.  At this point, most of the infection is present in the M63 group.  The foci are less than 1m, with several foci present in that group.  The infection is most severe on the third set of trifoliates, mostly in the low-mid canopy, but some up high.  The M63 group is near pod-fill (R5-7) with a canopy closure of 85%.  The M65 and M67 groups also showed signs of infection, but were to a much lesser extent.  Both of these groups are at the R2-3 stages and have a 100% canopy closure.  Some additional information:  this plot was planted on 36-inch rows with no Roundup applied (cultivated only), and stinkbug pressure is at a high level.  As a result, the plot will be sprayed accordingly next week.  I would rate the overall severity of the infection as light at this time, with localized infections light-moderate in the low-mid canopy. Jim Marois (UF Plant Pathologist) felt that the infection was in its second cycle, so it may have occurred in the plot as far back as two weeks." From Jim Marois, UF Plant Pathology: "The sentinel plot  was examined extremely closely by two people the Thursday before the find. When I visited the plots Friday the foci were obvious, as it was reported to be on Wednesday.  The first disease foci we could find were out less then 1 m in diameter, but they are very severely infected. It looks like short distance dispersal is dominant - these were in closed or nearly closed canopies. Just outside of the severe infection we usually could not find anything. Also, the infection was low in the canopy - none of the upper leaves were infected."

FL Find 6-27-05  Leon County, FL.  This find was in Tallahassee; Leon County is a new county for 2005, one county west of Jefferson County.   The find was confirmed by microscopy by FDACS-DPI and PCR by UF.  Updated map of 2004 and 2005 finds below (DPI).

Sentinel and observation plots in FL:  PDF map depicting the locations of survey sites being used to monitor SBR in Florida.  The primary and secondary sites were established are monitored by DPI inspectors and DPI & USDA CAPS personnel.  The sentinel sites were established by IFAS scientists and are monitored by them with some assistance from CAPS surveyors.  To date, 2005 detections are still limited to kudzu.  This SBR survey effort is succeeding due to the great cooperative efforts in the field, offices and laboratories of faculty and staff with UF/IFAS, USDA/APHIS/PPQ and FDACS/DPI.

New FL find 5-2-05  Dade County, FL.  These detections were on  kudzu leaves.  The finds were confirmed by microscopy by the FL Division of Plant Industry and by PCR by the UF Department of Plant Pathology.

   Positive Florida finds in 2005  (DPI)  (5-2-05)    The latest soybean rust find in FL is in Dade county on kudzu.  Dade county is to the far south and east of the previously identified counties.  This find was confirmed 4-29-05 by the Division of Plant Industry (microscopy) and UF, Dept of Plant Pathology (PCR).  The first 2005 detection of soybean rust in FL was a find 2/23 on overwintered foliage of kudzu in Dade City, Pasco Co. That is the most southerly find so far in FL. (T. Schubert, DPI)  Note that this map includes all finds to the present (2004-2005).  The 2005 finds are the yellow dots on the map.  These finds have been confirmed by DPI and UF-IFAS, Dept of Plant Pathology personnel using morphological and PCR techniques.

DPI map of positive counties in FL, 2004

Field Observations (CLH)

12-5-05  After a colder-than-normal weekend, I visited the kudzu site again and found very few green leaves left.  Much of the green in the images below consists of weed species other than kudzu.  Most of the bright yellow vining plants are air potato, not kudzu, although kudzu, turned brown by frost, is intertwined with the air potato.

12-1-05  Frost is finally descending on parts of Florida and most of the edible beans in our trials have been harvested.  The sentinel plots from this summer are finished, and new "overwintering" sentinel sites are being planned for this winter and spring.  These sites will most  likely be kudzu sites that were known to be positive during the 2005 growing season.  More information on that to come soon.  The large kudzu site in Marion county has been knocked back by frost; less than half of the leaf material remains attached to stems and the leaves that have fully senesced decompose rapidly on the ground.  However, those leaves that are still attached are heavily infected (see upper and lower leaf surfaces).  Other rusts on other hosts have been observed throughout this season, and images of those spores will be posted here soon.  The main take-home message from the variety trials is simple:  no soybean rust observed on anything besides soybean and kudzu here in FL.

8-24-05  For the sentinel plot in Marion County:  As of this week, I really can't differentiate the foci anymore; even the MG7s are looking pretty rough, although they and the MG5s still have leaves and some green tissue. Also, we have some weeds and cowpea volunteers starting to obstruct the view of the plot in its entirety. I have attached pictures from yesterday morning.

8-19-05  This is Take II, the second planting, and we have disease in the soybeans from the first round. The new set of beans were planted August 9th and most are already showing true leaves. It rained immediately after we finished planting, and granular fertilizer was spread early this week. Limas and cowpeas are a little spotty, but may fill in over the next week.  The varieties (15 total) that were planted (thank you to those of you who donated/sent seed!): Green beans: Ambra, Dusky, and Hystyle; Wax beans: Golden Rod, Gold Mine; Lima beans: Fordhook 242; Azuki beans; Soybeans: the same 4 as before, I just planted out what I had left; each variety is represented as a single 100' row of a group of four rows in each of the 4 blocks: Stressland, Ina, Williams, and Spencer; Cowpea: California Blackeye and Zipper Cream; Iron Clay Pea; Plus, the 4 soybean blocks from the last round will stay as a source of inoculum. However, some rows are nearly defoliated. There should be enough green tissue and viable inoculum to do the job, though.  The orders for black, pinto, navy, and kidney fell through, maybe next spring. I'd also like to try peas again, but it's way too hot for those right now...  I am still scouting once per week and all possible positives on anything but the soybeans (already tested) will be tested with ELISA and real-time PCR, and of course will be sent to Mary Palm, the federal identifier, if needed.  Item of interest this week: black-seeded cowpea volunteers growing in the soybean sentinel plot (which is heavily infected) appear to be disease-free, at least for now. They are just starting to flower, so I'll keep an eye on them. I should note that cowpeas are on the USDA host list. Photo of healthy cowpea and infected soybean below.  Weather - hot and dry this week, mid-90s, a few minor thunderstorms. The plot was irrigated (overhead) Monday and fertilizer was spread.

6-27-05  Near-daily thunderstorms and moderate temperatures over the last few days are conducive to spore germination.  Recent discussion about the destruction of positive sites in FL have indicated that some folks would like to know more about the size of the sites.  Please see the .avi file (can be played with Windows Media Player) which shows one site - Marion County, FL.  All together, this site, split by a dirt road, is estimated at around 4 four acres.  Video

6-22 and 23, 2005 Hot, dry weather has left even most of the inner canopy dry in the soybean sentinel plot in Marion County.  No Asian soybean rust in the soybeans or other beans yet. The kudzu site 3 miles to the east of the variety trial in Marion County is expanding and producing fresh spores of Phakopsora pachyrhizi, however. Weather in FL has been conducive for disease development up until the last few days, which have been in the 90s and dry.   I have found common bean rust (see image below) in a couple varieties in the variety trial (wax, snap, black turtle, and pinto beans). It's spotty right now, but an increase from last week - only the pinto beans last week.  Downy mildew (see image below) and a couple bacterial diseases (pustule and a little blight?) are visible on some of the soybeans.  Snap and wax beans are about 2 weeks from normal harvest (see image below). We will extend that to about 4 weeks to keep plants in the field as long as possible.

 6-15-05   New FL find   Jefferson County, FL.  The detection in on kudzu leaves and was confirmed by microscopy (UF/IFAS and FDACS-DPI), ELISA (UF/Plant Path), and real-time PCR (UF/Plant Disease Clinic).  The site is limited in size (under 1/4 acre).   See photos of the site, leaves, pustules and spores below.

6-13-05  Tropical Storm Arlene dumped rain and gusty winds on much of FL, especially north-central through the panhandle.  Warm, wet conditions were favorable for spore dispersal and germination.  FL personnel will be checking sentinel and mobile plots this week to get a baseline to compare next week's observations to.  This may be a good run to check hurricane effects on disease movement and development.

6-9-05  Marion County, FL:  Soybean sentinel plot is at R3-R4.  No rust found, but conditions are good for receiving inoculum from kudzu patch: wind blowing from the east at 10-15 mph, 75% cloud cover, temperature around 85 F, free water on many leaves of interior canopy.  Kudzu site (measured at 3.4 miles east of the sentinel plot) still expanding and there is evidence of new pustules and spore production (see photos below).  Bean variety trial soybeans and several other beans are flowering; soybeans are at R2.  No rust found.  Receiving samples of common bean rust from around the state (image below).  Easily differentiated from Asian soybean rust - Uromyces spp. pustules have reddish-brown color and appear on upper and lower leaf surface; thick, reddish-tan cell walls on urediniospores.

6-2-05  Marion County, FL:  Soybean sentinel plot is blooming and some plants are setting pods.  No rust found.  Some bacterial diseases (likely bacterial blight), downy mildew and insect feeding apparent.  Downy mildew bears striking resemblance to soybean rust, even with hand lens - see pictures below.  Kudzu site is expanding slowly, approximately 3 miles from the sentinel plot.  Incidence (how many leaves in an area) is estimated at 1-5%, severity (how much disease on an affected leaf) at 50% or more.  Affected leaves are more easily found in shaded areas and deep in the canopy in full sun areas.  Pustules are tan to reddish-brown and easily visible with the naked eye and 20X hand lens.   Bean variety trial showing insect feeding and possibly Cercospora on snap beans.  No rust found.  (CL Harmon) 

Images may be used for educational use and with permission.