1. Trellised Tomatoes and Drip Irrigation
SE Vegetable & Fruit Expo
December 2009
Bill Yarborough
NCDA&CS
Agronomic Division

2. NCDA&CS Agronomic Division Services
Plant / Waste / Solution/ Media Analyses
Soil Testing
Nematode Assay
Field Services

3. Field Services — 13 regions

4. NCDA&CS Soil Testing Measures soil pH and acidity
Measures nutrient reserves
Recommends lime application rates
Recommends fertilizer rates

6. NCDA&CS Plant Tissue Analysis
Measures nutrient concentrations
Monitors nutrient uptake
Finds deficiencies

7. Plant Analysis Sample latest mature, fully extended compound leaf.
Sample weekly, beginning when first fruit is the size of a dime.

8. Talk Today History of tomato production in WNC
Major nutrients discussed
Fertility recommendations
Contributors — Dr. Greg Hoyt (NCSU) and Steve Dillon (NCDA&CS)

9. History of Tomatoes in Western NC
Early 1950s
Staked tomatoes
Research on fertility based on high rates of nitrogen and little to no irrigation
Use of trellises began in late 1960s
Drip irrigation began in the 1980s

11. Nitrogen Important for vegetative growth Trellis varieties determinant
Excessive N can be a concern

12. Nitrogen Apply 40–60 lb/acre preplant.
Meet additional needs, as required, with drip.
Apply total of 90–130 lb/acre over the entire season.

13. Phosphorus Important for early growth
Soil test recommendations Can these be reduced?
Preplant application sufficient

16. Potassium (K) Critical for fruit quality
Preplant application insufficient
Application through drip essential

19. K Considerations K levels will be  4% ppm early in season.
K  2.5–3% is desirable at harvest.
K  2% produces soft fruit.
K  1% is unharvestable.

20. Calcium Important for blossom-end rot control
Soil test recommendations adequate
Adequate soil water essential

23. Blossom-end Rot and Control
Foliar sprays ineffective
Consider gypsum
Adequate soil water essential

24. Boron Important for potassium uptake Preplant application insufficient
Postplant applications required
Can be applied foliar or drip

26. Preplant Recommendations for Trellised Tomatoes
Soil test.
Apply P2O5, potassium, boron and lime as recommended.
Apply up to 60 lb/acre of N preplant.

27. N & K Drip Fertility Recommendations
Begin applying fertilizer when fruit is about the size of a dime.
Apply (or equivalent) at a rate of 20–25 lb/acre/wk.
Two weeks before first harvest, increase rate to 50 lb/acre/wk.
Once 50% of crop is harvested, begin reducing rate.

28. N & K Fertilization in Drip-irrigation system
Time of Application
N (lb/A)
K (lb/A)
Preplant
40–70
If deficient
1 wk > 1st fruit set (~ 30 days > planting)
3–4 / wk
10–12 / wk *
2 wks < harvest
6–7 / wk
20–25 / wk
Halfway into harvest
10–12 / wk
Approx. season total
90–130
170–205
* used to apply K and N in 3-to-1 ratio

29. Other Fertility Considerations
Low P2O5 levels at harvest should not be a concern.
Calcium levels should not be a concern with drip irrigation.
Boron levels should be between 40–75 ppm throughout harvest.

30. Quality Fruit Begins with Careful Fertility
Follow soil test recommendations.
Use plant analysis for monitoring.
Adequate water is essential.
Monitor key elements boron and potassium.

31. Trellised Tomatoes and Drip Irrigation
Bill Yarborough
NCDA&CS
Agronomic Division

32. For more information, browse the Agronomic Division Web site