| Field experiments were conducted to determine the critical period for weed control (CPWC) in non-grafted Amelia and Amelia grafted onto Maxifort tomato rootstock grown in plasticulture. The establishment treatments (EST) consisted of two seedlings of common purslane, large crabgrass and yellow nutsedge transplanted at 1, 2, 3, 4, 5, 6 and 12 wk after tomato transplanting (WAT) and remained until tomato harvest to simulate weeds emerging at different times during the season. The removal treatments (REM) consisted of the same weeds transplanted on the same d of tomato transplanting and removed at 2, 3, 4, 5, 6, 8, and 12 WAT to simulate weeds controlled at different times during the season. The beginning and end of the CPWC, based on a 5% yield loss of marketable tomato, was determined by fitting log-logistic and Gompertz models to the relative yield data representing REM and EST, respectively. The predicted CPWC, in the presence of a mixed population of weeds, was from 2.2 to 4.5 WAT in grafted tomato and from 3.3 to 5.8 WAT in non-grafted tomato. The length (2.3 or 2.5 wk) of CPWC in fresh market tomato was not affected by grafting, however, the CPWC management began and ended one wk earlier in grafted tomato than non-grafted tomato.;Greenhouse and field experiments were conducted to determine herbicide tolerance of grafted tomato. Although injury was observed from post-transplant applied herbicides in the greenhouse, no differences were observed in grafted and non-grafted tomato response including visual injury, plant height and fresh weight. Tomato injury at 3 wk after herbicide application increased from 3 to 13, 1 to 37 and 2 to 86% as rate of halosulfuron, Smetolachlor and metribuzin increased, respectively. In field experiments under plasticulture, fomesafen, halosulfuron, napropamide, and trifluralin pre-transplant initially caused greater injury to grafted tomato than non-grafted tomato regardless of rootstock (Anchor-T, Beaufort or Maxifort). However, by 4 WAT, no injury was observed in grafted and non-grafted tomato.;Greenhouse and field experiments were conducted to determine response of grafted eggplant on tomato rootstock to fomesafen, halosulfuron, S-metolachlor, metribuzin, napropamide, and trifluralin. No difference in injury from herbicides was observed in grafted and non-grafted eggplant in greenhouse and field experiments. Metribuzin applied posttransplant at 140 and 280 g ai ha-1 caused 94 and 100% injury to grafted and non-grafted eggplant 4 WAT. In field experiments, pre-transplant fomesafen, S-metolachlor, napropamide, and trifluralin caused less than 10% injury and no yield reduction in grafted and non-grafted eggplant. However, metribuzin caused higher injury and yield reduction in both grafted and non-grafted eggplant than other herbicides. Metribuzin at 550 g ha-1 caused 60 and 81% plant stand loss in 2013 and 2014, respectively. Halosulfuron reduced yield by 24% in both grafted and non-grafted eggplant compared to nontreated control in 2013 but did not reduce yield in 2014.;Greenhouse experiments were conducted to determine the efficacy of metribuzin on drought-stressed grafted and non-grafted tomato. Drought stress treatments included no drought stress, 3 d of drought stress before with no drought stress after metribuzin application (3 d DSB), and 3 d of drought stress before with 3 d of drought stress after metribuzin application (3 d DSBA). Metribuzin was applied at 550 g ha-1. No difference in injury from metribuzin was observed in grafted and non-grafted plants. However, at 7 and 14 d after metribuzin treatment (DMT), less injury was observed on tomato plants that were 3 d DSBA (5 and 2% injury, respectively) than on plants that were 3 d DSB(15 and 8% injury, respectively) or those that were not subjected to drought stress (18 and 11% injury, respectively). Photosynthesis rate and stomatal conductance were reduced similarly in grafted and non-grafted tomato when subjected to drought stress before metribuzin application. Photosynthesis and stomatal conductance of tomato at 7 DMT (3 d after rewatering) was not different among drought stress treatments or metribuzin treatments. Grafted tomato demonstrated similar tolerance as non-grafted tomato to metribuzin under drought stress conditions.;Experiments were conducted to evaluate absorption and translocation of halosulfuron in grafted and non-grafted tomato and eggplant. No differences were observed between the transplant types with regard to absorption and translocation of 14C-halosulfuron. Absorption of 14C-halosulfuron increased with time, reaching 10 and 74% of applied herbicide at 6 and 96 h after treatment (HAT), respectively. Translocation of 14C-halosulfuron was limited to the treated leaf, which reached maximum (66% of applied) at 96 HAT, whereas minimal (< 4% of applied) translocation occurred in scion shoot, rootstock shoot, and root combined. Results from this experiment indicate that grafting did not affect absorption and translocation of halosulfuron in tomato and eggplant. (Abstract shortened by UMI.). |
