staff of the Laboratory for Pest Control Application Technology.
Steven B. Polter, Douglas Doohan and Joseph C. Scheerens
A. M. Borowski, R. D. Morse and M. M. Alley
A Preliminary study conducted in 1985 indicated no significant yield response to 8 treatments ranging in amount of total N applied from 56 to 290 kg N/ha. Treatments in 1986 were as follows: base rate N at 0, 56, 112, and 168 kg N/ha with 0, 1, or 2 sidedressings at 56 kg N/ha each applied at 3 and 6 wks after seeding. Yield differences for base rate n were significant at the first harvest only, while sidedressing effects on yield were significantly different for 3 of the 4 harvests and total yield. Nitrogen uptake during the first 32 days after seeding (DAS) was minimal, 0.17 kg N/ha/day, but increased to 8.05 kg N/ha/day during head formation (55 to 77 DAS). Initial soil nitrate status was high in the top 25 cm (52 kg N3O /ha) but decreased to 10.6 kg NO3/ha in the control plot by the end of the season. Sidedressings, prior to and during head formation, are recommended to maintain an adequate available N supply throughout the growing season.
B. Marangoni, D. Scudellari and M. Toselli
Mature trees of Stark Redgold nectarines grown in silt loam soil in the Po Valley were tested at five fertilization regimes and compared to untreated control: N1 (100 kg N/ha), N1 (100 kg N/ha, split 60% in spring and 40%. in postharvest), N2 (200 kg N/ha), N1 (100 kg N/ha) + K (150 kg K2 0/ha), N2 (200 kg N/ha) + K (150 kg K2 O/ha). The annual distribution in spring was equally split before full bloom and at fruit set.
The data collected over the three trial years show no differences as compared to control in yield and fruit size. N2 delayed ripening and decreased fruit quality. Leaf mineral composition was affected by potassium; maximun N induced leaf accumulation of N-NH4 The high concentration of K in leaf tissues was correlated to the yellow color of the leaf blade. Total leaf chlorophyll content was measured by an Spad-502 chlorophyll meter (Minolta Corp.) and compared to that measured by conventional technique (Arnon method). The overall findings suggest the amount of N used in peach fertilization can be reduced.
Yanwen Gong and Theophanes Solomos
Previous research has shown that subjecting bananas to low O2 treatment during the climacteric rise decreases the rate of sugar accumulation but the fruits eventually ripen. In the present study we applied low O2 in fruits whose ripening had been initiated by exogenous C2H4 and in preclimacteric ones. In preclimacteric fruits low O2 suppressed the climacteric rise during the duration of the experiment (20 days). It completely inhibited the increase in sugars, invertase and sucrose phosphate synthase (SPS) activities while there was a sharp increase in sucrose synthase (SS). In control fruits the increase in sugar content coincides with a sharp increase in invertase, and SPS and a decline in SS. Hypoxia inhibited the increase in invertase and SPS while it induced an increase in SS. Nevertheless, the activities of invertase and SPS in the climacteric hypoxic fruits was higher than in hypoxic preclimacteric ones. The results, thus, indicate that the imposition of low O2 at the preclimacteric stage is much more efficient in delaying banana ripening than when it is applied after the initiation of ripening.
Peter Purvis, Calvin Chong and Glen Lumis
Plug-rooted liners of common ninebark [Physocarpus opulifolius (L.) Maxim.] were grown in 6-L nursery containers filled with 73% composted pine bark, 22% sphagnum peat moss, and 5% pea gravel (by volume). Plants were fertilized with Polyon (Nutryon) 17–5–12 (17N–2P–5K) 6-month controlled-release fertilizer at various rates (2.5, 4.5, 6.5, and 8.5 kg·m-3) pre-incorporated, topdressed, or dibbled (placed under the liner at potting). Plants were trickle-irrigated daily with low (0.4-L), middle (0.8-L), or high (2.0-L) volumes of water to maintain leaching fractions of <0.15, 0.25–0.35, or >0.60, respectively. Regression analysis indicated that growth of ninebark increased from 30 to 109 g/plant with increasing rates of incorporated fertilizer (mean over irrigation volumes), from 27 to 71 g/plant with topdress and from 59 to 103 g/plant with dibble. Electrical conductivity (EC, mean over five dates) of the leachate throughout the season was highest with dibble (0.85 dS·m-3), intermediate with incorporated (0.81 dS·m-3), and least with topdressed (0.76 dS·m-3). With low irrigation volumes, growth of ninebark increased from 42 to 81 g/plant with increasing rates of fertilizer (mean over methods), and from 39 to 105 g/plant with middle or high volumes (common regression curve). With low irrigation volumes, leachate EC increased from 0.74 to 0.94 dS·m-3 with increasing rates of fertilizer, and from 0.75 to 0.81 dS·m-3 with middle or high volumes.
Christopher A. Proctor, Matt D. Sousek, Aaron J. Patton, Daniel V. Weisenberger and Zachary J. Reicher
sequential application strategy compared with a full rate applied PRE when applied over multiple years at reduced rates. We found little published research on PRE crabgrass control when different a.i.s were used for initial and sequential applications
Donnie K. Miller, Thomas M. Batts, Josh T. Copes and David C. Blouin
epinastic symptomology 8 months after application. In a separate study, Clark and Braverman in 1998 also reported that glyphosate applied at 1/2, 1/4, and 1/10 of the use rate 27 d after transplant reduced ‘Beauregard’ U.S. No. 1 and total marketable yield
Bielinski M. Santos and James P. Gilreath
, and flow rates could be among the reasons for the inconsistent results. Duniway (2002) suggested that metam must be delivered carefully to avoid either leaching, when excessive water volumes are used, or rapid volatilization, with application of
Benjamin Wherley and Thomas R. Sinclair
counter high evapotranspiration rates of well-growing, highly maintained turfgrass may be the application trinexapac-ethyl (TE), a plant growth regulator ( Watschke et al., 1992 ). TE interferes with gibberellin biosynthesis and reduces laminar cell
Joshua J. Skelton, William Sharp and Bruce E. Branham
Minner, 2010 ; Reicher et al., 2011 ). Furthermore, Reicher et al. (2011) described postemergence control of ABG as inconsistent. The objective of this study was to determine the rate and application interval of mesotrione that will yield the greatest