Bareroot Corylus colurna were grown in 7.5-liter containers from 11 Apr. until 27 June 1994. The growing medium was fritted clay. Fertility levels included no fertilization, 100 ppm N, or 200 ppm N. Plants were root pruned to remove none or one-quarter to one-half of the primary roots. Root pruning at any level resulted in decreased height, shoot, and root dry weights and number and length of new shoots. One-quarter primary root removal resulted in lower root: shoot ratios compared to plants that were unpruned. One-half primary root removal further reduced root: shoot ratios. One-half primary root removal also reduced total leaf area compared to unpruned controls. Fertilization at 200 ppm N increased leaf numbers and total leaf areas compared to plants receiving no fertilization.
Patricia R. Knight, James R. Harris and Jody Fanelli
Maurus V. Brown, James N. Moore, William M. Harris and Patrick Fenn
Calcofluor and berberine were used to determine the potential of epifluorescence microscopy to observe the interaction between grape leaves and P. viticola. Leaf disks (10 mm in diameter) were inoculated and incubated for 2, 4, and 7 days. Disks were stained with berberine at 0.1% for 1 h, rinsed, placed in 0.1 M Tris (pH 5.8) for 15 min, stained in calcofluor at 0.1% for 25 min, and rinsed. Disks were mounted abaxial side up in 30% glycerin and viewed with an epifluorescence microscope. Various leaf features (e.g., trichomes, stomates) were distinguishable from the fungal structures (e.g., hyphae, sporangiophores). Leaf surface colors were red, orange, brown, green, and yellow, and fungal structures were light to dark blue. Epifluorescence microscopy was a useful means of differentiating leaf and fungal structures.
Robert Andrew Kerr, Lambert B. McCarty, Philip J. Brown, James Harris and J. Scott McElroy
Summer annual grassy weeds such as goosegrass (Eleusine indica L. Gaertn.) continue to be problematic to control selectively with postemergence (POST) herbicides within turfgrass stands. In recent years, reduced performance by certain herbicides (e.g., foramsulfuron), cancellation of goosegrass-specific herbicides (e.g., diclofop-methyl), and cancellation and/or severe use reductions of other herbicides [e.g., monosodium methanearsonate (MSMA)] have limited the options for satisfactory control and maintenance of an acceptable (≤30% visual turfgrass injury) turfgrass quality. Currently available herbicides (e.g., topramezone and metribuzin) with goosegrass activity typically injure warm-season turfgrass species. The objectives of this research were to evaluate both ‘Tifway 419’ bermudagrass [Cynodon dactylon (L.) Pers. ×Cynodon transvaalensis Burtt-Davy] injury after treatment with POST herbicides, and to determine whether irrigating immediately after application reduces turfgrass injury. Treatments were control (± irrigation); topramezone (Pylex 2.8C; ± irrigation); carfentrazone + 2,4-D + dicamba + 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP) (Speedzone 2.2L; ± irrigation); carfentrazone + 2,4-D + dicamba + MCPP in combination with topramezone (± irrigation); metribuzin (Sencor 75DF; ± irrigation); mesotrione (Tenacity 4L; ± irrigation); simazine 4L (±irrigation); and mesotrione + simazine (± irrigation). Irrigated treatments were applied immediately with a hand hose precalibrated to apply 0.6 cm or 0.25 inch (≈6.3 L). Visual turfgrass injury for combined herbicide treatments for the irrigated plots was 6% 4 days after treatment (DAT), 12% 1 week after treatment (WAT), 17% 2 WAT, and 6% 4 WAT, whereas nonirrigated plots had turfgrass injury of 14% at 4 DAT, 31% 1 WAT, 35% 2 WAT, and 12% 4 WAT. Irrigated pots had normalized differences vegetative indices (NDVI) ratings of 0.769 at 4 DAT, 0.644 at 1 WAT, 0.612 at 2 WAT, and 0.621 at 4 WAT, whereas nonirrigated plots had the lowest (least green) turfgrass NDVI ratings of 0.734 at 4 DAT, 0.599 at 1 WAT, 0.528 at 2 WAT, and 0.596 at 4 WAT. These experiments suggest turfgrass injury could be alleviated by immediately incorporating herbicides through irrigation.