Papers by Robert McGovern
Hortscience, Jun 1, 2000
Experiments conducted in January (hardwood cuttings) and June (softwood cuttings) 1998 compared r... more Experiments conducted in January (hardwood cuttings) and June (softwood cuttings) 1998 compared rooting and root dry weight (DW) of stem cuttings of three full-sib families of loblolly pine (Pinus taeda L.) rooted in Jiffy forestry peat pellets and Ray Leach Super Cells. Ray Leach Super Cells (vol.= 162 cm 3 ) served as the control and contained a medium of 2 peat : 3 perlite (v/v). Pellet sizes used were 25-65, 30-65, 36-65, 36-75, 42-65, 42-80, and 50-95 (dry diam.-expanded height in mm). Cuttings were taken from hedged stock plants and rooted for 12 weeks under mist in a humidity-controlled greenhouse. Following evaluation for rooting in the June experiment, ≈500 rooted cuttings in pellets and Ray Leach Super Cells were field-planted in eastern Georgia in December 1998 to study the effect of pellet size and cutting development on first-year field growth. Rooting percentages in January for hardwood cuttings rooted in pellet sizes 42-80 (36%) and 50-95 (57%) were less than the control (83%). Root DW for each pellet size was less than the control. Rooting percentage in June for softwood cuttings rooted in pellet size 36-65 (77%) was greater than the control (64%) whereas rooting percentages for cuttings rooted in pellet sizes 42-80 (50%) and 50-95 (52%) were less than the control. Root DWs for cuttings in pellet sizes 25-65, 30-65, 36-65, and 42-65 were less than the control. Field performance data will be presented. Two experiments were conducted to test the effects of early root pruning on growth of pin oak (Quercus palustris Muenchh.). Experiment one tested the effect of radicle tip removal when radicles had reached 5, 10, or 15 cm below the substrate surface. Total root length was not affected by treatment, but root-pruned trees had more large-diameter lateral (primary lateral) roots than trees that were not root-pruned. The number of primary laterals increased if the radicle tip was removed at more shallow depths. Experiment two tested the effect of liner production in bottomless containers (roots air-pruned) of 5-, 10-, 15-, and 20-cm depths on subsequent growth in #2 (6-L) containers. Top and root growth was generally lowest in 5-cm-deep containers and highest in 10-or 15-cm-deep containers.
Hortscience, Jun 1, 2000
The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, ... more The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, and Workshops). The Poster abstract numbers correspond to the Poster Board number at which the Poster will be presented.
Plant Disease, Sep 1, 2004
Hortscience, Jul 1, 2004
The Louisiana Dept. of Agriculture and Forestry (LDAF) conducts sweetpotato weevil [SPW, Cylas fo... more The Louisiana Dept. of Agriculture and Forestry (LDAF) conducts sweetpotato weevil [SPW, Cylas formicarius ( Fabricius )] monitoring in support of the statewide SPW quarantine program. The monitoring activity primarily involves a statewide pheromone-based trapping process that generates trap data for sweetpotato beds and production fi elds. We conducted GIS analysis of SPW trap data, collected over three years, to assess the potential use of GIS tools in managing and interpreting the data. The LDAF has already generated shapefi les for all beds and fi elds in each of three years, facilitating GIS analysis. However, trap data was manually collected and statewide data was compiled and stored in spreadsheet fi les. Trap data was mapped to specifi c beds and fi elds in each of three years, generating layers that clearly showed fi elds and parishes that reported high trap counts. GIS analysis showed potential SPW "hotspots" in each year, indicating that certain beds or fi elds are more prone to SPW infestation than others. This information can be useful in planning SPW management strategies by growers and other stakeholders. The GIS database also provides the foundation for the development of descriptive and predictive models of SPW occurence in Louisiana. Compiling the SPW trap data into a GIS database allows the data to be distributed over the Internet, facilitating real-time access by stakeholders. 2 Poster withdrawn. 3 Biofumigation Potential of Field Pennycress ( Thlaspi arvense ) Seedmeal Horticulture and Landscape Architecture
Hortscience a Publication of the American Society For Horticultural Science, 2007
Fusarium tuber rot, incited by Fusarium solani, is the major cause of losses of tuber quality and... more Fusarium tuber rot, incited by Fusarium solani, is the major cause of losses of tuber quality and quantity in caladium (Caladium ·hortulanum) during storage and production. To develop a reliable inoculation method for evaluating cultivar susceptibility to Fusarium tuber rot and identifying sources of resistance, the effect of temperature on the mycelial growth of F. solani in vitro and on tuber rot in vivo was examined. The optimal temperature was then used to study the aggressiveness of F. solani isolates. The effect of temperature (13, 18, 23, 28, and 33 8C) on radial mycelial growth of nine F. solani isolates in vitro was determined, and all responded similarly to temperature variables, with optimal growth predicted to be at 30.5 8C. The relationship of these temperatures to disease development was then determined for the most aggressive F. solani isolate 05-20 and it was found that disease development in inoculated tubers was greatest at low temperatures (13 and 18 8C). Cold damage to tubers was observed at 13 8C; therefore, 18 8C was chosen for all future disease screening. The aggressiveness of nine isolates was tested on two caladium cultivars. Significant differences among isolates were observed for the diameter of rotted tissue in both cultivars, indicating that choice of isolate was important for screening. Isolates 05-20 and 05-257 were highly aggressive on both cultivars. Tubers of 17 commercial caladium cultivars were inoculated with three isolates (04-03, 05-20, and 05-527) and incubated at 18 8C. The interaction between isolates and cultivars was highly significant (P < 0.0001), indicating that cultivars were not equally susceptible to different pathogenic isolates of F. solani. Lesion diameters differed significantly (P < 0.0001) among cultivars/isolates and ranged from 9.5 mm ('Rosebud' and 'White Christmas' for isolate 04-03) to 23.9 mm ('Carolyn Whorton' for isolate 05-20). The cultivars were ranked for susceptibility to tuber rot within each isolate and the normalized total rank for the three isolates was used to place cultivars into four categories
Plant Disease, 1998
in oaks in Florida and its association with growth decline in Quercus laevis. Plant Dis.82:569-572.
International Journal of Plant Sciences
ABSTRACT
Plant Disease
Numerous leaf spots and severe defoliation were observed in all Catharanthus roseus (L.) G. Don (... more Numerous leaf spots and severe defoliation were observed in all Catharanthus roseus (L.) G. Don (Madagascar periwinkle) plants in a landscape site in west central Florida. Leaf spots first appeared as small (1-2 mm) necrotic lesions most often associated with margins of leaves of all ages. As spots enlarged, they turned brown, became round to oblong (6.45 x 2 mm), and assumed a targetlike appearance. Eventually entire affected leaves turned yellow, then brown, and dropped prematurely. Hyphae and conidia of Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei were detected in symptomatic leaf tissue, and the fungus was consistently isolated from lesion margins on acidified PDA following disinfestation. Fungal conidia were olivaceous, obclavate to cylindrical, straight or curved, 40-190 um long, 8-22 um thick, 5-7 um wide at the truncate base, and had 4-16 pseudosepta. A 3-wk-old culture of C. cassiicola from periwinkle was comminuted in 500 ml of sterile, deionized water, and atomized on four periwinkle plants, which were enclosed in moist chambers. Inoculated plants and an equal number of noninoculated controls were incubated at constant day and night temperatures of 28 and 20 C, using a 14hr photoperiod. Leaf spots and defoliation identical to those observed in landscape plants appeared on all inoculated plants 7-10 days following inoculation, and C. cassiicola was reisolated from symptomatic tissue. This is the first report of infection of Madagascar periwinkle by C. cassiicola.
1. This document is SP159, one of a series
Fusarium crown and root rot (FCRR) caused by the fungus Fusarium oxysporum f. sp. radicis-lycoper... more Fusarium crown and root rot (FCRR) caused by the fungus Fusarium oxysporum f. sp. radicis-lycopersici (FORL), has consistently been the most important soilborne disease of tomato in southwest Florida, and has also been a sporadic problem in transplant production houses. Preplant fumigation with methyl bromidelchloro-picrin is the most commonly used management practice for soilborne pests in Florida, but even it provides incomplete control of FCRR. However, the designation of methyl bromide as a Class-l ozone depleter by the EPA and its impending phase-out necessitates evaluation of alternative management strategies for FCRR and other soilborne pests. This report summarizes research conducted in southwest Florida on the integrated management of FCRR over the past three years.
Additional index words. Bacillus subtilis, Pseudomonas aureofasciens, Streptomyces violaceousnige... more Additional index words. Bacillus subtilis, Pseudomonas aureofasciens, Streptomyces violaceousniger, fluazinam, PCNB, trifumizole. Abstract. A greenhouse experiment was conducted using 6week-old plants of impatiens (Impatiens wallerana J. D. Hook) 'Dazzler Scarlet Plush' planted in styrofoam trays containing a peat-based potting medium. Biological controls [Bacillus subtllis (Ehrenberg) Cohn (1.2 x 107 cfu/ml), Pseudomonas aureofasciens Kluyver (63-28r, 1.8 x 107 cfu/ml), or Streptomyces violaceusniger (Waksman and Curtis) Pridham et al. (5 x 105 cfu/ml)] were applied as soil drenches 14 days after planting (DAP). Fungicides [triflumizole (Terraguard 50 W, 0.3 g/l), PCNB (Terraclor 400,0.47 ml/I), or fluazinam (500 F, 0.125 or 0.5 ml/I)]
Dade County is a large metropolitan county approxi mately toe s\ze oi the state of Delaware. It h... more Dade County is a large metropolitan county approxi mately toe s\ze oi the state of Delaware. It has a diverse popu lation with over 50% living at the poverty level. Many people live in drab residences without access to areas offering aes thetic vegetative relief from their dreary environment. This project was initiated to alleviate stress in high crime areas and to develop neighborhood awareness.
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Papers by Robert McGovern