Part II: A Deeper Look into Grafted Watermelon Production and Management

In our last blog post we took a deeper look into grafted watermelon production and management by reviewing a 2020 watermelon trial in central North Carolina. In this post we want take you through year 2 results and our findings. The key focus points of the trial were increasing yields and maturity window of grafted plants using chloropicrin.

Trial details for background

• The trial was on watermelons grown on plasticulture using TIF film since we found the best results the year prior with using that.
• We made shank applied fumigant application using a Reddick Equipment Company RMC plastic layer 25 days prior to planting.
• The grower had watermelons on this particular piece of land on a 3 year rotation with sweet corn, small grain, and tomatoes.
• The land had heavy root knot nematode pressure and low fusarium wilt pressure so the Carolina Strong Back rootstock was used for the grafted watermelon plants.
• The trial was planted on 8’ row centers x 3’ standard plant spacing (1,815 plants/acre) and 8’ row centers x 4’ grafted plant spacing (1,316 plants/acre).
• We used 25% pollinators in-row between every 3^rd and 4^th seedless plant.

Harvest Events

• The trial fields allowed for 3 harvest events.
  • June 30 (74 DAP)
  • July 12 (88 DAP)
  • July 26 (102 DAP)
• The Joyride melon used is an 86 day melon.
• The grafted maturity is the same as the standard Joyride plant maturity, but heavier yields were shifted 5-7 days.
• We saw a strong yield response to the fumigant applications and vine health remained great all the way through final harvest on July 26^th.

In summary, we saw results similar to our findings in 2020.

• Chloropicrin is increasing yields in both non-grafted and grafted plant production systems
• Fertility changes and addition of chloropicrin are speeding up grafted plant maturity
• First harvest of grafted is approximately half of non-grafted, but the second harvest of grafted is much heavier
• Longer harvest windows are possible with grafted plants, due to increased plant growth and durability to harvests
• No significant differences were seen in size profiles or sugar content/brix between treatments

We saw comparable results in 4 different trials of similar design across North Carolina, Georgia and Florida in 2022. Some key findings:

Standard plant yields are increasing use of chloropicrin

• North Carolina – 34% increase
  • Florida – 16% and 15% increase
  • Georgia – 20% increase

Grafted plant yields are increasing with the use of chloropicrin and specific fertility protocols

• North Carolina – 22% increase
  • Florida – 12% and 23% increase
  • Georgia – 14% increase

Combining grafted plants and fumigation with chloropicrin is providing dramatic yield increases over grower standard practice yields in all trial areas

• North Carolina – 70% increase
  • Florida – 28% and 44% increase
  • Georgia – 28% increase

To learn more please contact our very knowledgeable team at TriEst and be sure to sign up for the next installation of the TriEst Ag News series.