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The success of a new high-density apple planting depends on how fast the grower can recoup the high investment that these systems require. The right balance between vegetative growth and cropping during the early life of the planting is where tree growth is sufficient to rapidly fill the allotted space while at the same time producing high early yields. In this study we evaluated irrigation or fertigation as strategies compared with the traditional nonirrigated control to improve growth and yield of five apple scion cultivars (Mutsu, Gala, Honeycrisp, Jonagold, and Macoun) on M.9 or B.9 rootstocks over the first 5 years at Geneva, NY. Calcium nitrate at the rate of 113 kg·ha−1 N was applied to all three irrigation treatments (dissolved in water for the fertigation treatment, broadcast dry with the irrigation treatment, or broadcast dry with the nonirrigated control). Our results showed that fertigation with dissolved N and irrigation with dry broadcast N increased yield and tree growth similarly and significantly over the first 5 years of orchard establishment compared with the nonirrigated treatment with dry broadcast N. There was a significant economic benefit of irrigation or fertigation in the humid climate of New York State.

Open Access

Eastern filbert blight (EFB) and pacific flatheaded borer (PFB) are two problems of Pacific Northwest orchard and nursery production. Fungicides and insecticides used to manage these issues are typically applied to plant tissues with minimal foliage present that can result in considerable spray waste or drift. The Intelligent Spray System (ISS) is a laser-guided, variable-rate sprayer that detects objects in the target zone and releases spray volumes proportional to the density of plant tissues, thereby increasing application efficiency and reducing waste. However, the ISS has not been tested when targeting low-foliage plant tissues such as emerging shoots and trunks. Three experiments were conducted from 2018 to 2021 to evaluate the potential use of the ISS for EFB and PFB management by assessing spray coverage on emerging hazelnut shoot tips, hazelnut tree trunks, and maple tree trunks. On hazelnut shoot tips, coverage was <10% of the shoot on both adaxial and abaxial sides, with the highest coverage on the adaxial side (9.5%) resulting from spraying in standard mode (no sensors) at 3.1 kph. On hazelnut trunks, application at the slowest tested speed (3.1 kph) in intelligent mode resulted in spray coverage greater than or equal to that applied in standard mode at 5.1 kph. In addition, coverage was significantly higher on cards placed on the ground between trees when the sprayer was used in standard mode, indicating higher amounts of wasted spray and drift over intelligent mode. On maple trunks, the slowest speed tested (3.1 kph) resulted in the highest coverage of tree trunks facing the sprayer that were two and three rows away from the sprayer, with the highest coverage levels on the row of trees closest to the sprayer occurring at the highest tested speed of 6.4 kph. On cards placed on trunk sides not facing the sprayer, the slowest tested speed of 3.2 kph resulted in significantly higher coverage than both treatments at 6.4 kph and intelligent mode at 4.8 kph in the tree row closest to the sprayer. This work has demonstrated a baseline of coverage that hazelnut buds receive when spraying for EFB, illustrates that the ISS was able to effectively target trunks, and could be an alternative to drenches for PFB control.

Open Access

Acquiring leaf gas exchange (LGE) data from field experiments is critical for numerous research endeavors. However, because of the extended time needed to perform measurements and the necessity for moving equipment, the number of leaf samples collected is often limited. To address this concern, two studies were conducted to evaluate the accuracy and efficiency of LGE measurements of excised and nonexcised strawberry leaves. Research was conducted in experimental field plots located in Lubbock, TX, USA, where ‘Camino Real’ strawberry leaves was sampled for LGE measurements, during the 2021 growing season. Using an auto program mode, two LI-6400/XT portable machines simultaneously measured the LGE of nearby selected leaves from the same plant. Measurements were recorded every 30 seconds. After 90 seconds, the petiole of one leaf was cut (excised leaf treatment), and the auto program continued for an additional 480 seconds. The results indicated that although the LGE for nonexcised leaves remained stable, excised leaf LGE changed after excision. Within 30 seconds, the postexcision stomatal conductance to water vapor (gsw ) and net leaf photosynthetic rate (A) exhibited nearly 97% and 99% accuracy, respectively, of nonexcised leaf gsw and A. However, the excised LGE decrease accelerated over time, with gsw continuing to decrease by more than 5% after 43 seconds, indicating ≤95% accuracy of the gsw results. The data suggested that strawberry LGE may be measured accurately within 30 to 40 seconds after leaf excision. During a separate experiment, the mean time to complete each individual strawberry LGE measurement was 68.4 seconds (±0.9 seconds) for nonexcised leaves. Conversely, the mean time to complete each LGE measurement of excised leaves was 42.2 seconds (±0.2 seconds). Therefore, leaf excision appears to be a viable method of maintaining accuracy and increasing the sample size while collecting strawberry LGE data.

Open Access

The future of agricultural water availability is threatened by climate change, population growth, and environmental regulations. Most of the global water is being used for crop irrigation. The objective of this research was to determine optimum timer-based controller settings and controlled-released fertilizer rates for ‘American Red’ (Pelargoium ×hortorum) potted geranium plants. Fertilizer was top-dressed at 3, 6, or 9 g. Plants were irrigated by a timer-based controller set to water at 11:00 AM every other day for 2 minutes, 9:00 AM and 2:00 PM for 1 minute per day, 11:00 AM for 1 minute per day, 11:00 AM for 2 minutes per day, and a control of manual hand watering. Data regarding plant growth, soil and leaf nutrients, and water use were collected. For geranium growth factors, the total flowers per plant was greatest for irrigation at 11:00 AM for 1 minute with 6 g fertilizer. Plant height and shoot dry weight were greatest for 6 and 9 g fertilizer. The number of umbels and soil plant analysis development (SPAD) chlorophyll meter readings were greatest for 9 g fertilizer. For geranium soil nutrient content, the pH was greatest for 3 g fertilizer, whereas the electrical conductivity, potassium, nitrate, sulfate, and boron were greatest for 6 and 9 g fertilizer. Regarding the nutrient content of the leaves, total nitrogen, boron, iron, and copper were greatest for 9 g fertilizer. Water use efficiency was greatest with 6 and 9 g fertilizer and irrigation 1 minute per day at 11:00 AM. The findings indicated that using timer-based controlled irrigation systems programmed to water for 1 minute during the morning with 6 g fertilizer resulted in plants that not only reduced water consumption but also enhanced water use efficiency and overall plant quality.

Open Access

Pawpaw (Asimina triloba) is a fruit-bearing tree native to North America, and nurseries have a strong public demand for grafted trees. Most nurseries currently propagate pawpaw cultivars clonally through chip budding and whip-and-tongue grafting, both onto pawpaw seedling rootstock. Flexibility in successful grafting and budding techniques can optimize the type and quality of available scionwood while using the available labor. In an initial experiment, a range of pawpaw selections were subjected to grafting and budding techniques that indicated candidate cultivars and advanced selections for further examination. Therefore, the objective of this study was to determine the optimal method of propagating the pawpaw cultivars, KSU-Atwood™, KSU-Chappell™, and the advanced selection Hi7-1 using chip budding, whip and tongue, T-budding, and a cleft grafting tool. Additional trees, each of KSU-Atwood™ and KSU-Chappell™, were also subjected to green budding in the summer with the current season’s scionwood. Whip and tongue grafting was the most successful method, with a scion survival rate (SSR) of 95.8%, followed by the cleft grafting tool (SSR = 66.7%) and chip budding (SSR = 50.0%), then T-bud grafting (SSR = 25.0%), and lastly green bud grafting (SSR = 0.0%). There were no cultivar differences for the grafting techniques used. The whip-and-tongue method had the highest scion survival rate; however, cleft grafting and chip budding can be effective propagation methods for nurseries if scionwood quality does not support the whip-and-tongue grafting technique. In addition to whip-and-tongue grafting, the cleft grafting tool is a viable option for grafting pawpaw for use by personnel with less grafting experience or skill.

Open Access
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GA3 is a common plant growth regulator used in production that can accelerate plant metabolism and significantly enhance the plant growth rate. We investigated the effects of exogenous GA3 on the physiological and biochemical indexes of Aglaonema under drought treatment. The effects of exogenous GA3 on the plant height, leaf blight rate, antioxidant enzyme activity, leaf pigment, and malondialdehyde content of Aglaonema were evaluated using Aglaonema ‘Red Ruyi’ as the test material and simulating natural drought treatment in nutrient soil pots. The spraying of exogenous GA3 significantly increased superoxide dismutase and peroxidase enzyme activities, promoted the accumulation of soluble sugars, reduced the accumulation of malondialdehyde, and slowed the decline of chlorophyll and carotenoids, which had good effects such as the reduction of the leaf wilting rate and increase in the plant height as well as the maintenance of the plant shape to maintain the ornamental appearance. The growth indexes such as plant height and wilting rate were mainly influenced by the changes of the leaf pigment and physiological and biochemical indexes of malondialdehyde.

Open Access

‘Marquette’ is a cold-hardy hybrid grape cultivar that has received increased attention for its use in wine production in the upper midwestern and northeastern United States since it was released in 2006. However, ‘Marquette’ is an early budburst cultivar susceptible to spring freeze damage. We examined the influence of high wire bilateral flat cane (HWC) and four-arm Kniffin (4AK) training systems on young ‘Marquette’ performance during a year with spring freeze damage (2017) and the subsequent season without frost events (2018). In 2017, there were two consecutive spring frost events at the experimental site approximately 2 weeks after the vines reached 50% budburst, which damaged more than 70% of the shoots. The percentage of freeze-damaged shoots and the severity of freeze damage to green tissues did not differ between training systems, but 4AK vines had higher yield at harvest (5.16 kg/vine or 3.12 tons/acre) than HWC vines (3.45 kg/vine or 2.10 tons/acre) because of the greater number of buds retained at winter pruning. There was no freeze damage close to budburst in 2018, and the yield of 4AK vines was still higher (11.74 kg/vine or 7.08 tons/acre) than that of HWC vines (8.20 kg/vine or 4.98 tons/acre). In 2018, the Ravaz index (yield-to-pruning weight) values were lower for HWC vines (3.41) than for 4AK vines (5.39), but the training system did not consistently affect fruit composition in either vintage. Within the 4AK system, shoots that emerged from the lower cane had more freeze damage than those of the upper cane and produced lower crop yield and fruit with lower soluble sugars in both vintages. Our results suggest that ‘Marquette’ vines can be grown on a training system with high cropping potential, such as a divided canopy system or a single canopy, with a higher number of buds and shoots than that of our study. Among divided canopy systems, 4AK might not be the best option for vigorous ‘Marquette’ vines because, in addition to greater susceptibility to freeze damage, the lower cane of 4AK was highly shaded by the upper highly vegetative canopy, which might have caused its lower productivity and soluble sugars at harvest compared with those of the upper cane.

Open Access

Two field experiments were carried out in 2022 and 2023 within commercial watermelon fields in Stockton and Modesto, CA, USA. Two Trichoderma-containing products were applied to the grafted and nongrafted watermelon seedlings through tray soaking or field chemigation. All seedlings were mechanically transplanted into a split-split plot design with the Trichoderma product as the main factor and application method (tray soaking and chemigation) as the sub-plot. The sub-sub-factor included three interspecific hybrid squash rootstocks (Cucurbita maxima × Cucurbita moschata) ‘Cobalt’, ‘Flexifort’, and ‘RS841’ that were grafted with the commercial seedless watermelon scion ‘Summer Breeze’. All treatments were replicated four times. Vine health was visually assessed three times, and canopy coverage was assessed for a total of six measurements for each year. Harvest was conducted three times in 2022 and twice in 2023 to analyze yield and quality differences among treatments. Aboveground and root samples from defective plants were taken amid the harvest and shipped to the University of California, Davis Fungal Pathology Diagnostics Research Laboratory for identification of soilborne fungal pathogens to confirm or rule out their involvement in vine declines initially attributed to nonpathogenic factors. The laboratory diagnosis indicated that Macrophomina was morphologically identified from the foot and root isolations of 67% of the submitted nongrafted, non-Trichoderma-biofungicide–treated plants in 2022. Further sequencing results confirmed the primary pathogen, Macrophomina phaseolina, from 50% of those submitted plant samples. In addition, putative Fusarium root and stem rot (Fusarium oxysporum f. sp. radices-cucurmerinum) and Falciforme crown rot and decline (Fusarium noneumartii) from runners and roots of nongrafted, noninoculated plants in the 2022 experiment were also reported. However, no significant soilborne fungal pathogens were found in the 2023 experiment. In both trials, the effects of Trichoderma-containing biofungicides and their application methods on preventing vine decline, maintaining canopy coverage, and enhancing fruit yield and quality were not as remarkable as grafting. The average grafting effect contributed to 83% and 53% decrease of vine decline compared with the nongrafted plants in 2022 and 2023. Overall, grafted plants yielded 47.6% and 32.4% more than the nongrafted counterpart in 2022 and 2023, respectively. In addition, grafting exerted predominant influence on fruit firmness and rind thickness. The study results indicated that grafting onto multipathogen resistance watermelon rootstocks serves as an effective production tool to maintain fruit yield, quality, and plant health under both pathogenic and disease-free conditions. Further work is still needed to continue evaluating best practical application protocols of Trichoderma-based biofungicides and other biopesticides to enhance product effectiveness and end users’ confidence in reducing soilborne diseases and reliance on conventional fumigants.

Open Access