V e g e t a r i a n  N e w s l e t t e r
   A Vegetable Crops Extension Publication
    Vegetarian 03-11  November 2003
   Print Version

Ambra, an Exceptional Potato Variety for Florida

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.

(Josh Mayfield, extension agent & Tim Momol, assistant professor - Vegetarian 03-11)

Trifloxysulfuron (Envoke) Labeled on Tomatoes

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.

(Stall - Vegetarian 03-11)

Update of Problems from Herbicide Row-middle Applications in Tomatoes

(Stall - Vegetarian 03-11)