This is a challenging year. Due to the COVID-19, we only implemented one biostimulant trial. We collaborated with BioWorks, Inc. to evaluate the use of a biofungicide (Root Shield Plus) and biofertilizer (On-Gard) alone or in combination to impact watermelon growth and yield production. Three application treatments plus a nontreated control was arranged in a commercial watermelon field in Turlock. All application followed manufacturer recommended rates at the following timings as a foliar spray. Each treatment row is 40 feet long containing 7 seedless plants and 2 pollenizers. Watermelon plants were placed in single rows of 80-inch wide beds with 6 feet apart.
| Treatments | Timings |
| RootShield Plus and On-Gard (RSP and OG) | Rootshield: 2 and 6 weeks after transplanting; On-Gard: 2 weeks after transplanting and then every other week until before the first harvest |
| RootShield alone (RSP) | 2 and 6 weeks after transplanting |
| On-Gard alone (OG) | 2 weeks after transplanting and then every other week until before the first harvest |
| Non-treated control | Same volume of water was applied at each product application. |
Two harvests were conducted on July 15 and 29, 2020. Fruit were weighed, counted, and fruit from the first harvest were brought to the lab for quality analysis, including Brix, rind thickness, fruit length and width, and hollow heart rating. Also, leaf chlorophyll concentration and NDVI were measured throughout the season. The data are included in the following tables except for NDVI readings.
Fruit yield from the first and second harvest on July 15 and 29, 2020.
Treatment | Total number per plot | Total weight (lbs. per plot) | Avg. fruit wt. (lbs.) | |||
| 1st harvest | 2nd harvest | 1st harvest | 2nd harvest | 1st harvest | 2nd harvest |
RSP and OG | 17 | 9 | 336 | 183 | 20.2 | 21.3 |
RSP | 16 | 9 | 300 | 186 | 18.8 | 20.9 |
OG | 16 | 13 | 338 | 292 | 20.7 | 22.9 |
Non-treated control | 11 | 6 | 228 | 135 | 20.1 | 22.2 |
P value | 0.38 | 0.04 | 0.30 | 0.05 | 0.02 | 0.63 |
LSD0.05 | 7 | 5 | 145 | 111 | 1.5 | 3.1 |
Fruit quality measured using the fruit from the first harvest.
Treatment | Brix | Rind thickness (mm) | Width (in.) | Length (in.) | Hollow heart | Chlorophyll conc. (umol/m2) |
RSP and OG | 12.3 | 14.6 | 10.6 | 11.4 | 2.0 | 593 |
RSP | 12.2 | 16.3 | 10.6 | 11.3 | 2.2 | 637 |
OG | 12.2 | 15.2 | 10.8 | 11.3 | 2.0 | 632 |
Non-treated control | 12.0 | 12.7 | 10.7 | 11.5 | 1.2 | 659 |
P value | 0.82 | 0.01 | 0.55 | 0.86 | 0.17 | 0.43 |
LSD0.05 | 0.60 | 1.70 | 0.41 | 0.63 | 1.01 | 93 |
Yield from the combination of the two harvests.
Treatment | Total number per plot | Total weight (lbs. per plot) | Avg. fruit wt. (lbs.) |
RSP and OG | 25 | 519 | 20.4 |
RSP | 25 | 485 | 29.5 |
OG | 29 | 631 | 21.7 |
Non-treated control | 17 | 362 | 20.8 |
P value | 0.05 | 0.02 | 0.08 |
LSD0.05 | 7 | 135 | 1.6 |