Kathryn Fontenot, Johnson, Charles E. | 2/19/2014 11:03:39 AM
Tomatoes continue to be one of the most popular spring vegetable crops grown by both Louisiana homeowners and commercial producers. Unfortunately this popular crop is also susceptible to tomato spotted wilt virus (TSWV) during the early spring months.
TSWV is transmitted by thrips. Insecticides do not generally help prevent this virus because transmission is almost instantaneous once thrips pierce into the tomato plant. Some growers will use aluminum-coated mulch as a deterrent. The aluminum-coated mulch reflects an enormous amount of sunlight; making it difficult for insects to see the crop. Other growers plant resistant varieties. Resistant varieties are an excellent option for homeowners who plant few tomato plants each year.
The LSU AgCenter established several demonstration plots throughout the state to study newer TSWV-resistant tomato varieties. The purpose was to determine if a particular TSWV-resistant variety yielded better than others and also to see if any were susceptible to TSWV.
Nine TSWV-resistant tomato varieties were grown in four locations throughout Louisiana. Selected varieties included Tribute, Tribeca, PSO1522935, Amelia, Primo Red, PSO1522942, Red Bounty, Crista and Red Defender. Demonstration locations included farms located in Livingston, West Feliciana and East Baton Rouge parishes. Intensive data was collected at the Botanic Gardens at Burden in Baton Rouge, La. Other participating fields were evaluated after harvest began. All participating farmers were asked to grow the tomatoes on plastic mulch, using drip irrigation and to incorporate a conventionally based fungicide spray program to prevent infestation of disease. The following will explain specific production techniques implemented at the TSWV-resistant tomato variety field at Burden.
Tomato transplants were planted into the field on March 12, 2013. Two freezes occurred after planting. Prior to each freeze, tomato transplants were covered with weather-protection cloth. The field was fertilized with 8-24-24 prior to planting at a rate equivalent to (600 lbs/acre). The tomatoes were grown on aluminum-coated plastic mulch with drip irrigation. Irrigation was applied daily for 30 minutes. Irrigation schedules will vary from farm to farm depending on soil type.
Dual herbicide was applied to control weed infestation in row middles.
Tomatoes were sidedressed weekly from bloom initiation for five weeks, alternating between calcium nitrate and potassium nitrate. PCNB was applied as a drench at the beginning of the season to prevent southern blight infestation.
Tomatoes were placed on a weekly fungicide spray schedule. Insecticides were used as needed. All chemicals were applied at recommended rates as labeled in the Southeastern U.S. Vegetable Crop Handbook. Fertilizer rates were applied at recommended rates in the Louisiana Commercial Vegetable Production Guide.
Tomatoes were single-drilled and planted at 18-inch spacings within the row. Four replications of each variety were planted, 12 plants within each replication. A skip row was left open between every two planted rows to obtain optimum spray coverage when applying chemicals.
Harvest data was collected for five weeks during peak production to capture total yield for all tomatoes. Yield included marketable and unmarketable fruit and was sorted with weights recorded separately. Fruit was harvested weekly. Plant size, foliage coverage, exterior color, interior color, firmness, cracking, fruit size and yield were also recorded.
A field day was held at Burden with 193 people participating in a taste test. The taste test winner was Tribeca. The top 3 producing tomatoes were Tribute with 80% marketable yield, Tribeca with 82% marketable yield and PSO1522935 with 84% marketable yield. None of the tomato varieties tested exhibited symptoms of TSWV throughout the growing season.
General comments on each variety are provided below. Please note pounds per acre are estimated based on yields in our trial. Assume each acre is planted skipping every third row for ease of spraying, with tomatoes on 18-inch centers within rows.
Tribute: Tribute seed was purchased from Seedway. Foliage and firmness were rated as excellent on these plants. The exterior color of the fruit was red to orange, with a red interior color. Fruit size was small to medium, and the total pounds produced per acre were 38,950 with 80% being marketable fruit.
Tribeca: Tribeca seed was purchased from Seedway. The foliage and firmness were rated as good-plus to excellent. The fruits' exterior color was red with a pale red interior. The fruit had very few cracks and were small to medium in size. 34,920 lbs of fruit per acre were produced with 82% of total yields being marketable. This variety won the taste test and produced more tomatoes in number than all other varieties.
PSO1522935: PSO1522935 seeds were purchased from Harris Seed. Foliage firmness and cracking were rated as excellent. The exterior color was orangey-red with a dark red interior. Fruit size was small to medium, producing 26,136 lbs per acre. 84% of total yield was marketable.
Amelia: Amelia seeds were purchased from Harris Seed. Foliage was rated as good and fruit firmness as excellent. The fruit did not crack. Fruit size was medium. 25, 834 lbs/acre can be produced with 78% being marketable.
Primo Red: Primo Red seed was purchased from Harris Seed. Foliage was rated as good and fruit firmness was excellent. There were very few cracks in the fruit. Exterior color was orangey-red with a pale red interior. Fruit size ranged from small up to large. 25,350 lbs/acre was produced. 79% of total yield was marketable. This variety did not trellis well at any location.
PSO1522942: PSO1522935 seed was purchased from Harris Seed. Foliage was rated as good-plus with excellent fruit firmness. The fruit did not crack. Exterior color was red with a dark red interior. Fruit size was medium. 25,083 lbs/acre were produced. 89% of total yield was marketable.
Red Bounty: Red Bounty seeds were purchased from Harris Seed. Foliage and fruit firmness were rated as excellent. The fruit cracked very little. Fruit size was small to medium with a red exterior and interior color. 24,394 lbs/acre were produced with 72% of the total yield being marketable.
Crista: Crista seed was purchased from Harris Seed. Foliage was rated as good; fruit firmness as excellent. The fruit did not crack. Exterior fruit color was red with a red interior color. Interior color was notably marked with white splotches. 24,378 lbs/acre were produced with 71% of total yield being marketable.
Red Defender: Red Defender seed was purchased from Harris Seed. Foliage and fruit firmness were rated as excellent. Fruit did not crack. Fruit size ranged from small to large with an orangey-red exterior color and red interior color. 18,888 lbs/acre were produced with 88% of total yield being marketable.