by Steve Bogash, Horticulture Extension Educator/Researcher | Penn State University Presented at the 2015 Minnesota Statewide High Tunnel Conference.

1. TOMATOES: WHAT’S NEWS AND
MAKING THE END OF THE SEASON
WITH GREAT TOMATOES
Steve Bogash
Horticulture Educator / Researcher

2. Laying out a plan for the entire season
• What was in the field / tunnel last season?
• Preplant soil testing
• What varieties have and have not worked for
you?
• Applying nutrients:
– Regular granular
– Slow release
• Staying ahead of consumption curves.

3. Tomato Nutrition Problems
Plus, yields less than #20 of marketable fruit per plant

4. Defining Terms
• Soil pH
– pH = potential of hydrogen
– Greatly affects the availability of nutrients
– Relative acidity / alkalinity
– pH of 7 is considered neutral
– Tomatoes grow best at 6.2-6.5
– Logarithmic scale
– Test both soil and irrigation water
• We often add acid(s) to irrigation water

5. Additional important terms
• Sufficiency: Moving target that varies from
carrying a crop to carrying a profitable crop.
Usually expressed as a percentage.
• Deficiency: Not enough nutrient present to
satisfy even the most minimal plant needs.
• Toxicity: Overabundance to the point of
damaging a plant or causing other nutrients to
be out of balance.

6. Putting together a fertility plan
• Know your soil or potting media
– Regular testing by a laboratory is the only accurate
tool.
– Test the soil before planting
– Test the soil again at the onset of flowering
– How have the key nutrients changed (N, P, K, Ca
and Mg) as the plants use these nutrients?
– Plow down 30-50% of overall needs at bed
workup.
• Organic growers will want to plow down 60-80% why?

7. Know your water
• Test water 1st use for:
– pH*
– Alkalinity*
– N, P & K
– Clogging particulates
– Fe
• Regularly test for pH and Alkalinity
• Well vs. Spring vs. Stream vs. Pond

8. Stages of a tomatoes life
• Planting - Rapid increase in vegetative mass
• 1st flowering
– Flower bud initiation begin heavy K drop
• This is prior to you seeing the first buds
• Development of fruit
– P drops rapidly as fruit begin to size
• Ripening of fruit
• Continued development of flowers and fruit
(indeterminate plants only***)
• Determinate types 2nd fruiting potential

9. Seedling fertility program
• No fertilizer at seeding
• First true leaves: 75-100 ppm N balanced
• 4-6 weeks: 100-150 ppm N
• 6-8 weeks: 150 ppm N
• 8 weeks: transplant and test

10. Early (vegetative) Growth
• 20-20-20 or 20-10-20 up until initiation of flowers.
• 3-4-3 fish-based fertilizer is the same
• Plant tissue analysis at first flower.
• Tissue analysis:
– 10-15 whole leaves
– Collect from average plants
– Collect 4-5th leaf from top
• Most recent mature leaf
– Paper bags only!
– Overnight or pickup
– Take leaf below top flower cluster on determinate types.

11. Nutrition at flowering (two weeks prior)
• Plant tissue analysis
• Adjust fertility program to 3-4K+ / 1N
• Bring Ca to 100% sufficiency
• Adjust Mg to Ca by using a ratio of 2-4 Ca to 1
Mg.
• K+ needs to be above 3% by dry matter

12. Plant maintenance
• Monitor N, K+, P, Ca & Mg levels
• Monitor irrigation water pH weekly
– With hydroponic systems, monitor daily or
constantly
• Weather considerations
– Day length
– Relative sun / cloud cover
– Day / night temperature variations
• Creating high quality fruit requires careful
irrigating.

13. Most growers primary packout
challenge:

14. How much fertilizer?
• Apply #.5 (minimum) actual N / acre / day to
1.5 acre tomatoes. We’re using 20-20-20.
Applied every other day.
• .5 x 1.5 = .75 (fertilizer for the area / day)
• .75 x 2 = 1.5 (N needed over 2 days)
• 1.5 / .2 = #7.5 (amount of 20-20-20) every 2
days
• This could have been solved in almost any
order and still gotten to #7.5.

15. More fertilizer math
• Let’s work with 9-15-30
– Still use #.5 / acre actual N and same size field
(1.5A)
– #.5 x 1.5 = .75 (Actual N for field per day)
– .75 x 2 = 1.5 (N needed over 2 days)
– 1.5 / .09 = #16.7 of 9-15-30 every 2 days
– If N is still high (above 4%) at next tissue test, one
option is to change to 8-16-42 (KSC-Timac).

16. My tunnel standards
• BrandyBoy
• Scarlet Red
• Primo Red
• Red Bounty
• Red Deuce
• Red Mountain
Primo Red

17. Nutrition at flowering
• Plant tissue analysis
• Adjust fertility program to 3-4K / 1N
• Bring Ca to 100% sufficiency
• Adjust Mg to Ca by using a ratio of 2-4 Ca to
1 Mg.
• K+ needs to be above 3% by dry matter
– I refer to this as chasing potassium
• Nutrients: 9-15-30 (Miller Nutrichem)or 8-16-
42 (Timac) plus Nutri K (Potassium
Carbonate) or 4-10-40 foliarly
– We increased drip irrigated nutrients weekly
based on tissue tests and often still fall behind.

18. What are we doing to keep up?
• Plow down of aragonite (approximately 38% Ca) at soil prep
– Good source of slow Ca release
• Plow down of green potash (15% K) at soil prep
– This may be the trick to keeping K levels up
– This practice worked well in 2012, 2013 & 2014
• Foliar applications of Ca, Mg and K as needed
– Synergism between foliar K and soil K
• Ca is non mobile in plant
– What does this mean for nutrient application?
• Mg must be there with Ca
– Epsom salts at soil prep at #30-100 / acre

19. More on Ca
• Since it is non-mobile:
– Must always be in solution
– Tissue analysis is Monday AM refereeing for Ca
– Constant application necessary or
• Aragonite
– Since Ca is actually Ca++, you must use chelated
forms foliarly.
• Formulation matters in getting nutrients past the
cuticle or through the stomata

20. More on Mg
• Must be in solution in a 3/1 ratio with Ca.
• Mg SO4 (epsom salts) are great for soil
preparation, but lousy for in-season
immediate fixes.
• Look for MagSi, MgO, Mg Citrate, or Magical

21. Getting your Potash numbers up
• Along with applying enough
– Your soil solution pH must be between 6.2 and 6.5
– Potash availability drops quickly outside of this
range
– Start early and stay with an aggressive program.
• Getting it there:
– Inject sulfuric acid whenever irrigating or
fertigating
– Organic alternative: Citric acid
– You must work with a calibrated pH meter

22. Some notes of phosphorus consumption
• Through tissue testing we’ve noted a
precipitous drop in P levels immediately after
the first fruit set.
– Combining 12-48-8 with 9-15-30 for 2-3 weeks has
brought our tissue tests back into the sufficiency
zone.
– Not sure what specific effect these low P levels
have on plant yield, but overall vigor is
immediately evident in bringing levels up.

23. Where does soil biology fit into this discussion?
• Higher levels of active fungi make a huge
difference in nutrient uptake by plant roots.
– Bacteria too, but to a lessor extent than fungi.
– Specific type of fungi makes a huge difference
• Most commonly mycorrhizal types.
• Trichoderma spp. have similar effects to mycorrhizae
• All organic matter is not created equally
– Carbon / Nitrogen (C/N) ratio matters
• Very high C / N ratio will use much of the N to degrade
the carbon.

24. Disease management in a tomato tunnel
• Challenges:
– Septoria leaf spot
– Late Blight
– Bacterial Canker
– Leaf Mold
– Powdery Mildew (late season)

25. My nimble management program:
• Mancozeb or Regalia-based until first harvest
is in sight.
• Then Regalia-based due to mancozeb 5 day
PHI
• Basic program:
– Day 1: Regalia
– Day 5: Actinovate AG
– Day 10: Stimplex or other biostimulant
– Day 15: start over

26. Upping the ante’
• Regalia + copper, then Actinovate AG +
Stimplex on 7 day schedule.
• Add in B.subtillus product for enhanced PM
and LM control.
• Regalia + Ranman, Curzate, Tanos, or P. Flex
for enhanced LB management.
• Inject Regalia + GreenStim + Actigard foliarly
for enhanced bacteria mgt.

27. Our goal

28. THANK YOU
YOUR QUESTIONS PLEASE!
Steve Bogash
Horticulture Educator
smb13@psu.edu
717-240-6500 ext 6507