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  • Author or Editor: Patrick A. Jones x
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‘Mini Blues’ highbush blueberry (Vaccinium sp.) was released in 2016 as a high-quality, machine-harvestable alternative to lowbush (V. angustifolium Ait.) or other small-fruited highbush blueberry cultivars for processed markets. A planting was established in Oct. 2015 in western Oregon to evaluate the effects of pruning method on yield, machine-harvest efficiency (MHE), berry weight and total soluble solids (TSS), leaf tissue nutrients, pruning weight, pruning time, and costs. Plants were pruned for shape and to remove flower buds in 2015–16 and 2016–17. Pruning treatments began in 2017–18 and included: 1) conventional highbush pruning (HB); 2) removing one or two of the oldest canes per bush (Speed); 3) leaving plants to grow from 2017 to 2021 (Unpruned) before doing a hard renovation prune in 2021–22 (cutting the plants back to a height of ≈0.3 m and leaving the best 8–10 canes/plant); and 4) hedging after fruit harvest in 2018 (Hedge) and then unpruned afterward until renovation in 2021–22. The pattern of yield progression, observed wood aging, and reduced berry size after 4 years of no pruning indicated renovation was necessary in the unpruned and hedge treatments. Low growth was removed each year in all treatments, and hedging was only done in 2018 because it severely reduced yield the following year and, therefore, was not a viable option. An over-the-row machine harvester was used from 2018 to 2021. Speed-pruned plants, averaged over 4 years, had the greatest potential yield (3.75 kg/plant) compared with the other treatments (averaged 2.99 kg/plant) but had a similar yield as HB because more fruit remained on the bush after harvest with speed pruning. In 2021, speed pruning resulted in the highest yield (4.2 kg/plant), followed by HB (3.8 kg/plant) and the unpruned and hedge methods (averaged 3.1 kg/plant). MHE increased from 43% in 2018 to 74% in 2021, mainly because, as the plants aged, a larger proportion of the canopy was above the catcher plates on the harvester. On average, MHE was highest with HB pruning (70%), intermediate in the unpruned and speed-pruned plants (59%), and lowest in the hedged plants (49%). In 2021, ground drop loss was highest for hedge (18%), lowest for speed (14%), and intermediate for HB and unpruned (averaged 16%) methods. HB-pruned plants had heavier berries (0.64 g) than unpruned and hedge treatments (averaged 0.57 g) and a similar berry weight as the speed-pruned plants (0.61 g). Pruning had no effect on berry TSS. In contrast to leaf K, leaf Mg and Ca concentrations were lowest in HB and higher in all other treatments. In 2020–21, HB pruning required 471 h·ha−1, while speed pruning took 79 h·ha−1; the hedge and unpruned treatments required an average of 60 h·ha−1 to remove low-growing branches that would interfere with machine harvest. In 2021–22, renovation of the unpruned and hedge treatments took 290 h·ha−1. While leaving bushes unpruned during establishment appears to be a promising option for ‘Mini Blues’, further work is needed to evaluate fruit production after renovation and to determine how long the plants could remain unpruned thereafter. Speed pruning is also a good option, reducing pruning costs by 85%.

Open Access

Divoting is a common occurrence on golf courses and athletic fields. Research was conducted at the University of Tennessee Center for Athletic Field Safety (Knoxville, TN) during 2012–13 evaluating the effects of preemergence (PRE) herbicide applications on hybrid bermudagrass [C. dactylon (L.) Pers. × C. transvaalensis Burtt-Davy, cv. Tifway] divot resistance and recovery. Plots were subjected to the factorial combination of seven herbicide treatments (indaziflam at 35 and 52.5 g·ha−1; prodiamine at 840 g·ha−1; pendimethalin at 3360 g·ha−1; dithiopyr at 560 g·ha−1; oxadiazon at 3360 g·ha−1; non-treated control) and three divot timings [1, 2, and 3 months after herbicide treatment (MAT)]. Rates were based on label recommendations for preemergence crabgrass (Digitaria spp.) control. Herbicides were applied on 15 Mar. 2012 and 2013. Divots were generated using a weighted pendulum apparatus designed to impart 531 J of impact energy to the turf sward with a golf club. Divot resistance was quantified by measuring divot volume at each timing while divot recovery was quantified by measuring turf cover in the divot scar using digital image analysis. All herbicide-treated plots produced divots with volumes ≤ the non-treated control. In 2013, volumes were greater for divots produced 1 MAT (215 cm3) than those created 2 MAT (191 cm3) or 3 MAT (157 cm3). No differences in divot recovery were detected as a result of herbicide treatment in either year. Under the conditions of this study, applications of PRE herbicides at labeled rates did not affect divot resistance or recovery.

Chemical names: N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1-yl]-6-(1-fluoroethyl)-1,3,5-triazine-2,4-diamine (indaziflam), 2,4 dinitro-N3,N3-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine (prodiamine), N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin), S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate (dithiopyr), 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon)

Free access