e g e t a r i a n N
e w s l e t t e r
A cooperative variety evaluation project was conducted by the University of Florida and HZPC America’s Corp. (http://www.hzpc.ca) in 2003 at the PSREU-Hastings. A goal of this trial was to evaluate the production characteristics of early generation clones and advanced varieties from HZPC in Florida. Many of HZPC’s European lines have unique quality characteristics that could broaden the definition of “new” Florida potato beyond the standard Red LaSoda!
One promising variety evaluated was ‘Ambra’, a yellow-flesh European gourmet type potato (Fig. 1). Because of limited seed supplies, ‘Ambra’ was grown from mini-tubers. 'LaChipper' and 'Yukon Gold', two local standards, were grown from standard seed pieces. Potatoes were planted on 30 January, 2003. Plants were vine killed and tubers harvested 14 May and 2 June, 2003. A total of 230-43-197 lb/A of N-P2O5-K2O were applied in a split application during the season.
‘Ambra’ produced a marketable yield similiar to that of ‘Yukon Gold’ (Table 1) with similar low incidence of external and internal defects (Table 2). Although the stand and early vigor of ‘Ambra’ was reduced because the selection was grown from mini-tubers, the overall appearance was better than both ‘LaChipper’ and ‘Yukon Gold’ (Table 3). Variety evaluation trials will be conducted on several grower farms in the 2004 season.
For complete production details and a list of all varieties and clones tested, visit http://potato.ifas.ufl.edu and click on ‘2003 Florida Chip and Fresh Potato Variety Trial Report’.
* 'Ambra' was grown from mini-tubers. 'LaChipper' and 'Yukon Gold' were grown from 2.5 oz seed pieces.
(Hutchinson- Vegetarian 03-11)
Bacterial Wilt Research Update
Until recently, research with southern bacterial wilt (Ralstonia solanacearum) has been carried out in the field (Fig. 1 and Fig. 2). However, since August 2002, researchers at the North Florida Research and Education Center (NFREC) - Quincy have been monitoring irrigation water from surface sources to determine if ponds used for watering tomato plants are actually reproductive environments for spread of this disease. Several surface irrigation ponds in the north Florida tomato production region have been found to harbor considerable quantities of the bacterial wilt pathogen during the fall 2002 production season. By November and December 2002, pathogen levels in these ponds had declined to low and undetectable levels, respectively. However, sampling resumed again in April 2003 and by this past May and June, Ralstonia spp. was found again in concentrations as high as 1000 bacterial cells/mL of pond water. During a 2-hour irrigation event, this number grows exponentially in the soil. However, now there are several things known about this problem and recommendations that can help you make sound decisions for managing the disease on your farm:
1. If you are irrigating from a surface water source, submit a water sample to the Plant Diagnostics Laboratory at the NFREC-Quincy so that diagnosis of Ralstonia spp. can be made. Take subsamples from approximately 4 areas of your pond that are relatively close to the banks and send these to the lab.
2. It is known that Solanaceous plants (such as nightshade) in ponds, on pond banks, and in fields are sources of Ralstonia spp., and if these plants are properly identified and controlled, bacteria levels will drop. Remember that 1 infected plant can put 1 million bacterial cells back into local water sources!
3. If Ralstonia spp. has a history in your fields (25%+ infection), using cover crops such as rye and oats in the winter, and corn and sorghum-sudangrass hybrids in the summer will help manage weeds and may break the disease cycle in one or more years.
4. Finally, growers with Ralstonia spp. on their farms should be chlorinating the surface irrigation water so that the concentration of free chlorine in the drip tubes at the furthest end of each row is 5 parts per million (ppm). Concentrations of chlorine will of course depend on cleanliness of water and organic matter present in drip lines.
For assistance with sampling your ponds, contact the NFREC Plant Disease Diag. Lab, Quincy at (850)875-7140.
Trifloxysulfuron, (Envoke herbicide) has received a label for use as a post-directed spray on transplanted tomatoes. Envoke can be used as a postemergence-directed spray application in transplanted tomatoes at 0.1/0.15 to 0.2 oz product per acre (0.007-0.014 lb ai) grown on plastic mulch. The application should be made prior to fruit set and at least 45 days prior to harvest. A high quality non-ionic surfactant (NIS) should be added at a rate of 0.25% v/v. The post emergence application will control small weeds species including bristley starbur, coffee senna, Florida beggarweed, hemp sesbania, lambsquarter, several morningglory species, yellow nutsedge and partial control of purple nutsedge, many pigweed species, ragweed, sicklepod and several other weeds.
Research in the state has shown that
application of Envoke over the top of small tomatoes can temporarily stunt the
plants. If the herbicide is not applied to the growing points, but applied to
the lower parts of the plants, no damage has been noted, nor yield loss seen.
This fall there have been at least four instances of tomato damage linked to applications of herbicide or herbicide combinations in row middles. The first thoughts were that it was due to a combination of Dual Magnum and Aim applied to the row middles. Now Aim has been exonerated and the use of Dual Magnum is being looked at.
The damage is similar to damage caused by other chloroacetamides herbicides sprayed over the top of tomatoes (Fig. 1). The problem is that this type of damage has not been seen when Dual Magnum has been applied over the top of tomatoes, nor is it similar to the phyto from pre or ppi applications of Dual Magnum applied at extremely high rates. The tomatoes do outgrow the initial injury.
One thought is that the damage is caused by volitalization of the herbicide in the row middles. Neither I nor Syngenta research can duplicate the injury. I have placed tomato plants in pots surrounding pans of Dual Magnum mixes in greenhouses. The solutions have evaporated, but no damage was noted on any tomato plant. Field applications also have not duplicated the injury. The injury also has not been seen on a large number of commercial applications using Dual Magnum.
One common factor of all the areas where injury has been seen is that the fields have been very wet. In one instance, a part of the field that was wet had injury symptoms, but another area of the field that was not as wet (better drained) did not show the injury symptoms. The rows ran from wet to dry areas so the injury was seen down the row, eliminating application changes.
Syngenta is aware of the problems, and have been trying to establish the cause of the problem. They are not pulling the label for row middle application, but also are not pushing this type application until the cause of the problem can be identified. I believe that everyone should be aware of the wet field conditions being linked to the problems and that applications should not be made to wet row middles.
If anyone has other thoughts on this problem, please let me know.
- Vegetarian 03-11)
Extension Vegetable Crops Specialists