Average percentage (n = 5 ± standard error) of harvested sweetpotato after four treatments assigned to three categories, market: marketable root size and quality, cull RKN: culled because of root-knot nematode damage, and cull other: culled because of non-nematode causes_ Field trials during 2016 (cultivar ‘O’Henry’) and 2017 (cultivar ‘Beauregard’) at SCREC, Irvine, CA_
| Sweetpotato yield (%) | ||||||
|---|---|---|---|---|---|---|
| Treatment | Market | Cull RKN | Cull other | |||
| 2016 | ||||||
| 1. Untreated Control | 6.6 ± 4.3 | ba | 70.3 ± 8.1 | a | 23.3 ± 6.0 | b |
| 2. Metam-sodium (294 liter/ha) | 5.3 ± 2.3 | b | 66.3 ± 6.9 | a | 28.5 ± 7.4 | b |
| 3. Fluensulfone pre-plant (3.36 kg/ha) | 28.3 ± 5.3 | a | 16.4 ± 5.5 | b | 55.4 ± 3.8 | a |
| 4. Fluensulfone pre-plant (3.36 kg/ha) and 2× post (1.68 kg/ha + 1.68 kg/ha) | 35.1 ± 2.9 | a | 12.0 ± 2.1 | b | 53.0 ± 4.3 | a |
| Treatment P-value | 0.0001 | 0.0043 | 0.003 | |||
| 2017 | ||||||
| 1. Untreated Control | 29 ± 8.0 | c | 58 ± 9.4 | a | 13 ± 3.0 | a |
| 2. Metam-sodium (294 liter/ha) | 37 ± 4.0 | bc | 44 ± 7.0 | ab | 19 ± 4.3 | a |
| 3. Fluensulfone pre-plant (1.96 kg/ha) | 54 ± 6.6 | ab | 35 ± 7.6 | bc | 11 ± 5.1 | a |
| 4. Fluensulfone pre-plant (2.8 kg/ha) | 70 ± 3.2 | a | 21 ± 2.9 | c | 9 ± 2.9 | a |
| Treatment P-value | 0.005 | 0.02 | 0.27 | |||
Average (n = 5) vigor of sweetpotato cultivars O’Henry (2016) and Beauregard (2017) in four treatments 20 and 50 d post-plant_ Field located at SCREC, Irvine, CA1_ Vigor rating from 1 to 10 (very poor − excellent) ± standard error_
| Vigor rating (days after planting) | ||
|---|---|---|
| Treatment | 20 | 50 |
| 2016 | ||
| 1. Untreated Control | 7.4 ± 0.89 | 7.2 ± 0.84 |
| 2. Metam-sodium (294 liter/ha) | 8.0 ± 0.71 | 7.8 ± 0.45 |
| 3. Fluensulfone pre-plant (3.36 kg/ha) | 7.6 ± 0.89 | 7.6 ± 0.55 |
| 4. Fluensulfone pre-plant (3.36 kg/ha) and 2× post (1.68 kg/ha + 1.68 kg/ha) | 7.8 ± 0.45 | 7.6 ± 0.55 |
| treatment P-value | 0.62 | 0.56 |
| 2017 | ||
| 1. Untreated Control | 4.8 ± 0.49 | 6.0 ± 0.32 |
| 2. Metam-sodium (294 liter/ha) | 6.0 ± 0.89 | 6.2 ± 0.37 |
| 3. Fluensulfone pre-plant (1.96 kg/ha) | 7.2 ± 0.66 | 7.2 ± 0.37 |
| 4. Fluensulfone pre-plant (2.8 kg/ha) | 6.4 ± 0.81 | 6.4 ± 0.40 |
| Treatment P-value | 0.19 | 0.20 |
Average yield (n = 5 ± standard error) of harvested sweetpotato after four treatments assigned to three categories, market (marketable size and quality), cull RKN (culled because of root-knot nematode damage), and cull other (culled because of non-nematode causes)_ Field trials were conducted during 2016 (cultivar O’Henry) and 2017 (cultivar Beauregard) at SCREC, Irvine, CA1_
| Sweetpotato Yield (kg/plota) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Treatment | Total | Market | Cull RKN | Cull other | ||||
| 2016 | ||||||||
| 1. Untreated Control | 14.9 ± 1.5 | bb | 0.8 ± 0.4 | b | 10.5 ± 1.5 | a | 3.6 ± 1.2 | b |
| 2. Metam-sodium (294 liter/ha) | 19.7 ± 5.0 | b | 0.9 ± 0.3 | b | 11.7 ± 1.5 | a | 7.0 ± 3.5 | b |
| 3. Fluensulfone pre-plant (3.36 kg/ha) | 29.6 ± 3.5 | a | 8.2 ± 0.2 | a | 4.6 ± 1.3 | b | 16.8 ± 3.0 | a |
| 4. Fluensulfone pre-plant (3.36 kg/ha) and 2× post (1.68 kg/ha + 1.68 kg/ha) | 29.8 ± 3.0 | a | 10.1 ± 0.4 | a | 3.6 ± 0.7 | b | 16.1 ± 2.6 | a |
| Treatment P-value | 0.01 | 0.0001 | 0.0003 | 0.006 | ||||
| 2017 | ||||||||
| 1. Untreated Control | 24.8 ± 2.7 | a | 6.7 ± 1.9 | b | 15.0 ± 3.9 | a | 3.1 ± 0.6 | a |
| 2. Metam-sodium (294 liter/ha) | 27.7 ± 2.8 | a | 9.9 ± 1.0 | b | 12.5 ± 2.7 | a | 5.3 ± 1.2 | a |
| 3. Fluensulfone pre-plant (1.96 kg/ha) | 34.0 ± 2.4 | a | 18.4 ± 2.6 | a | 12.0 ± 2.6 | a | 3.5 ± 1.4 | a |
| 4. Fluensulfone pre-plant (2.8 kg/ha) | 33.0 ± 3.6 | a | 23.3 ± 3.4 | a | 7.1 ± 1.4 | a | 2.6 ± 0.8 | a |
| Treatment P-value | 0.13 | 0.002 | 0.32 | 0.30 | ||||
Average root-knot nematode levels (n = 5 ± standard error) in soil and on harvested sweetpotato after four treatments_ Field trials during 2016 (cultivar O’Henry) and 2017 (cultivar Beauregard) at SCREC, Irvine, CA_
| J2 per 100 g soil | ||||||
|---|---|---|---|---|---|---|
| Treatment | Pre-plant (Pi) | Post-plant (Pf) | Eggs per g sweetpotato | |||
| 2016 | ||||||
| 1. Untreated Control | 23 ± 16 | aa | 198 ± 42 | a | 536 ± 38 | a |
| 2. Metam-sodium (294 liter/ha) | 12 ± 5 | a | 300 ± 61 | a | 573 ± 133 | a |
| 3. Fluensulfone pre-plant (3.36 kg/ha) | 14 ± 6 | 173 ± 51 | a | 79 ± 17 | b | |
| 4. Fluensulfone pre-plant (3.36 kg/ha) and 2x post (1.68 kg/ha + 1.68 kg/ha) | 14 ± 8 | a | 156 ± 33 | a | 98 ± 34 | b |
| Treatment P-value | 0.95 | 0.29 | 0.0001 | |||
| 2017 | ||||||
| 1. Untreated Control | 21.2 ± 9.1 | a | 360 ± 107 | a | 304 ± 46 | a |
| 2. Metam-sodium (294 liter/ha) | 25.0 ± 12.3 | a | 261 ± 52 | a | 228 ± 87 | a |
| 3. Fluensulfone pre-plant (1.96 kg/ha) | 34.4 ± 14.4 | a | 396 ± 80 | a | 37 ± 16 | b |
| 4. Fluensulfone pre-plant (2.8 kg/ha) | 49.0 ± 17.8 | a | 532 ± 132 | a | 21 ± 5 | b |
| Treatment P-value | 0.65 | 0.54 | 0.0005 | |||