Craig H. Canaday and Jim E. Wyatt

Tomato varieties BHN 444 and BHN 555 with reported resistance to tomato spotted wilt virus (SWV) and two experimental lines with reported TSWV resistance, HMX800 and HMX9800, were compared against the popular tomato variety Mt. Fresh in a small variety trial. BHN 555 flowered earlier than the other four entries and grew more quickly than all athe other entries except BHN 444. TSWV was not observed in any of the entry rows. Entry losses to Sclerotinia stem rot did not differ significantly. There were no significant differences among the entries in total marketable yields or the yields of large and extra-large tomatoes. Highest early and season-long yields were with BHN 555.

In the 2000 growing season, the marketable yields of many West Tennessee tomato growers were greatly reduced by an outbreak of tomato spotted wilt virus (TSWV). This outbreak was prompted by unusually high numbers in the spring of western flower thrips, one of the important insect vectors for TSWV. Some tomato producers experienced >90% yield loss in their early harvests. Growers became extremely interested in any tomato variety or line with TSWV resistance. This tomato variety trial was initiated to examine the horticultural adaptability of such lines to West Tennessee growing conditions.

Site description. The soil in the test field was a Calloway-Henry silt loam complex, 0-2T slope with 1% O.M., high soil test levels of available P, and moderate to high soil test levels of available K. The soil contained over 1280 lb Ca/acre, over 64 lb Mg/acre, and approximately 5 lb Zn/acre. Soil pH in plots ranged from 6.8 to 7.3 with a mean pH of 7.0 (fall 2000 soil tests). Pelletized Dolomitic Limestone with a Tennessee Relative Neutralizing Value (RNV) of 98.2 was hand-broadcast Feb 4, 1002, as needed over each 5 x 50 ft. plot at rates recommended by the fall 2000 soil tests.

Experimental design. The 2001 test was a randomized incomplete block design with four replications. Each rep contained four of the following five tomato varieties or lines; BHN 444, BHN 555, HMX 800, HMX 9800, and Mt. Fresh. Experimental units were one-row tomato plots with eight plants spaced two feet apart per row. The plots constituted the north and south border rows of a much larger no-till tomato test. All entries were seeded in 72-cell Speedling trays filled with Pro-Mix BX on March 26.

Cultural practices. Nitrogen fertilizers at 15 lb N/4356 row-ft were applied seven times: once as ammonium nitrate in 30-inch-wide strips down the center of each plot (April 11, 3 ˝ weeks before setting transplants), five tiems as calcium nitrate in 18-inch-wide bands on each side of rows (May 8 and 18; June 5, 113, and 21), and once as urea at 9.8 lb N/4356 row-ft in 18-inch-wide bands on each side of rows (June 27). All plots were fertilized twice with sulfate of potash at a30 lb K₂0/4356 row-ft per application, once 3 ˝ weeks before setting transplants and again as a sidedressing one month after transplanting.

Herbicides, supplemented with occasional mowing or hand-hoeing, were used for weed control. Roundup-Ultra at 1.5 quart/acre (2.0% solution) was applied down the center of each plot in 30-inch-wide bands on March 115, April 5 and May 3. The last spray was applied one day before setting transplants to kill emerging yellow nutsedge.

The test was planted on the afternoon of May a4 using a modified mechanical transplanted equipped with a furrow-opening shank and two 100-lb weights to help close the furrow. Plants were suckered once. When needed to avoid moisture stress or to dissolve sidedressed fertilizers, plots were irrigated using a drip irrigation system consisting of 0.5 gallon/hr emitters spaced every two feet along side tomato rows. Plants were tied to stakes using a modified ‘Florida weave’.

Poast at 1.5 pint/acre was applied as a directed spray (18-inch-wide bands) on each side of rows on June 8. Sencor 75 DF at 1.25 lb/acre was applied as a directed spray on each side of the tows on June 12 (15-inch-wide bands). Fungicides were applied four times using a hydraulic sprayer; three applications of Quadris 2.08 SC at 5.8 - 6.2 fl oz/acre/application (on May 25, June 18 and July 24) plus one application of Bravo WeatherStik at 1.3 quart/acre (on June 29). Insecticides were applied five times; SpinTor 2SC at 5.8 fl oz/A on May 25 and Asana XL at 7.0 - 9.6 fl oz/acre on June 18, June 29, July 24, and July 30. All fungicide and insecticide sprays were applied at 300 psi using a hydraulic sprayer equipped with one to four (depending on plant height) ceramic, hollow-cone drop nozzles on each side of rows.

Data collection. The number of flowers/plant was recorded May 16. Plant heights were recorded June 6 and 20. Plots were checked every 1-2 weeks for the presence of any diseases, and disease incidence or severity ratings were collected as appropriate. Tomatoes were picked 2-3 times/week from June 29 through August 7 at the ‘breaker-stage’ of maturity (12 harvests). A final (13^th) harvest of all remaining green tomatoes of marketable size was made on August 9. Harvested tomatoes of marketable quality were graded by size into four categories; small (7 x 7 boxes), medium (6 x 7 boxes), large (5 x 6 boxes), and extra-large (4 x 5 boxes). Yields (boxes/acre) in the following tabes are based on 3600 plants/acre. Small tomatoes were considered unmarketable and are not included in yield tables. All disease, growth, and yield data were subjected to analysis of variance (ANOVA) for an experiment with an incomplete block design.

Results and Discussion

There were significant differences among the entries in early flowering on May 16 and mean plant height on June 6 (Table 1). BHN 555 appeared to flower earlier than all the other entries. Both HMX lines appeared to flower earlier than Mt. Fresh. Both BHN varieties were significantly taller than Mt. Fresh on June 6. By June 20, these significant differences had disappeared..

Three tomato diseases were observed in the adjoining no-till tomato test during the spring and summer of 2001; Sclerotinia stem rot (white mold), southern blight, and tomato spotted wilt virus. Of these three diseases, only Sclerotinia stem rot was present in the border-row variety test reported here. Plant losses due to this disease ranged from 4 to 12% with no significant difference between entries (Table 1).

There were no significant differences among the entries in tomato size and total marketable yields (Table 2). If, however, yields are corrected for differences in plant loss due to Sclerotinia stem rot, then Mt. Fresh and BHN 555 produced significantly more small tomatoes than BHN 444 and HMX 9800 (Table 3). Expressing yields in this manner did not lead to any differences in large or extra-large fruit or total m arketable yields. There were also no significant differences in entry yields when examined by harvest period (Table 4).

Table 1. Flower number, plant heights, and disease losses of tomato entries, Jackson, TNB, 2001

*Values are the means of 3-4 rows/entry. Means followed by a different letter are significantly different (P = 0.05).

Table 3. Effects of tomato entry on marketable yields of staked tomato, June 29 -0 August 9 (13 harvests), Jackson, TN, 2001.

Table 4. Effects of tomato entry on marketable yields of staked tomato, Jackson, TN 2001 - by harvest period.*

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Copyright © 1999 by The University of Tennessee. All rights reserved.

This research represents one season's data and does not constitute recommendations.  After sufficient data is collected over the appropriate number of seasons, final recommendations will be made through research and extension publications.