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  • Author or Editor: B.B. Clarke x
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Abstract

Lilies (Lilium longiflorum Thunb.) were treated with ancymidol (A-Rest), propiconazol (Banner), triadimefon (Bayleton), or Mobay RSW0411 as a soil drench or as a preplant bulb soak. At high rates the fungicides triadimefon and propiconazol reduced Easter lily plant height. Neither propoiconazol nor triadimefon were as effective as Mobay RSW0411 or ancymidol in reducing plant height; however, results suggest that chemical treatments for disease and height control may be achieved with the same treatment. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); 1-(2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl)-1H-1,2,4-triazole (propiconazol); 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)-2-butanone (triadimefon); β-(cyclohexylmethylene)-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (Mobay RSW0411).

Open Access

Take-all patch, caused by Gaeumannomyces graminis (Sacc.) Arx. & D. Olivier var. avenae (E.M. Turner) Dennis (Gga), is a disease of creeping bentgrass (Agrostis stolonifera Huds.), which most often is associated with golf courses. Synthesis of ligneous and phenolic compounds by plants requires adequate Mn+2 and Cu+2 nutrition and may be a factor in disease resistance. An experiment was conducted on a creeping bentgrass fairway naturally infested with Gga to determine if foliar applications of Mn+2 (1.02 and 2.04 kg·ha–1 per application) and Cu+2 (0.68 kg·ha–1 per application) would reduce take-all severity. Prior to initiating treatments, soil pH was 6.4 and Mehlich-3 extractable Mn+2 and Cu+2 were 5 mg·kg–1 and 1.7 mg·kg–1, respectively. Manganese and copper sulfate treatments were initiated in July 1995 and foliarly applied every 4 weeks through 1997 with the exception of December, January, and February. Disease incidence was decreased from 20% on untreated turf to 5% with the high rate of MnSO4. For both years, turf treated with the high rate of Mn+2 had less disease than turf receiving the low rate of Mn+2. The application of CuSO4, however, did not influence disease development.

Free access

Rusts are destructive fungal diseases that can cause severe thinning and unattractive discoloration of kentucky bluegrass (KBG; Poa pratensis L.). Currently, turfgrass breeding programs rely on field evaluations to screen KBG germplasm for rust resistance; methods that are expensive, labor intensive, and require large turf areas. The availability of a greenhouse-based assay to perform prescreening of KBG germplasm for resistance to rust diseases before field trials would allow breeders to remove the poorest performing plants before field evaluations thus enhancing breeding efficiency. In this study, we set out to develop a reliable, low-cost greenhouse inoculation protocol for the two most common rust pathogens of KBG in temperate growing regions: Puccinia coronata and Puccinia graminis, the causal agents of crown and stem rust, respectively. Using a modified inoculation assay and custom-built plexi-glass chambers adapted from protocols used for cereal rust pathogens, urediniospores of crown and stem rust fungi developed on inoculated plants 10 to 14 days postinoculation. Real-time polymerase chain reaction (PCR) assays, disease symptomology, and morphology of urediniospores confirmed the presence and identity of both rust pathogens from inoculated host tissue. The inoculation protocols described here represent an effective method to accelerate screening of KBG germplasm for resistance to crown and stem rust diseases. Infection of KBG plants in the greenhouse will also allow breeders to maintain populations of crown and stem rust fungi throughout the year, providing a reliable and ongoing source of pathogen inoculum for experimentation and screening in the future.

Free access

Sand size can affect the ability to incorporate topdressing into the turf canopy and thatch on golf course putting greens; unincorporated sand interferes with mowing and play. This 3-year field trial was initiated to determine the effects of sand size on sand incorporation, surface wetness, and anthracnose (caused by Colletotrichum cereale Manns sensu lato Crouch, Clarke, and Hillman) of annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] maintained as a putting green. The experimental design was a randomized complete block with four replications; treatments included a non-topdressed control and three topdressing sands (medium-coarse, medium, or medium-fine) applied every 2 weeks at 0.15 L·m−2 during the summer. Topdressing with medium-coarse sand was more difficult to incorporate than the medium and medium-fine sands, resulting in a greater quantity of sand collected with mower clippings. Analyzing the particle distribution of sand removed by mowing confirmed that coarser sand particles were more likely to be removed in mower clippings. Surface wetness measured as volumetric water content (VWC) at the 0- to 38-mm depth zone was greater in non-topdressed plots than topdressed plots on 35% of observations. Few differences in VWC were found among sand size treatments. Turf responses to topdressing were not immediate; however, as sand accumulated in the turf canopy, topdressed plots typically had lower anthracnose severity than non-topdressed turf after the first year. Additionally, topdressing with medium and medium-fine sands produced similar or occasionally lower disease severity than topdressing with medium-coarse sand. The lack of negative effects of medium and medium-fine sands combined with better incorporation after topdressing and less disruption to the putting surface should allow golf course superintendents to apply topdressing at frequencies and/or quantities needed during the summer to maintain high-quality turf and playing conditions.

Open Access

Anthracnose, caused by the fungal pathogen Colletotrichum cereale Manns sensu lato Crouch, Clarke & Hillman, can be a damaging disease on many cool-season turfgrasses; however, it has not been reported as an aggressive pathogen on fine fescue species (Festuca spp.). Symptoms and signs associated with anthracnose disease were observed in fine fescues on the Rutgers University Plant Science Research and Extension Farm in Adelphia, NJ, in Jun 2014. The objectives of this study were to identify the causal agent, determine if the isolate of C. cereale (FF1A) obtained from symptomatic Chewings fescue (Festuca rubra L. ssp. commutata Gaudin) plants was pathogenic to Chewings fescue and hard fescue (F. brevipila Tracey) turfs, and whether cultivars and accessions collected from Europe varied in disease susceptibility. Pathogenicity of this fine fescue isolate was evaluated using four Chewings fescue and four hard fescue cultivars or accessions in a growth chamber. Disease symptoms were first observed at 5 days post-inoculation, and evaluations continued to 17 days post-inoculation. Infection was confirmed by morphological evaluations, re-isolation from symptomatic tissues, and real-time polymerase chain reaction (PCR). Three noncommercial accessions (two Chewings fescues and one hard fescue) were very susceptible to the fine fescue C. cereale FF1A isolate, whereas ‘Sword’ and ‘Beacon’ hard fescues exhibited low susceptibility. In addition, an isolate of C. cereale (HF217CS) from annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] was included, and our data demonstrated that this isolate was also able to infect Chewings fescue and hard fescue. This study confirmed that C. cereale can be a damaging pathogen of fine fescues, and that breeding for resistance to anthracnose should be considered when developing new cultivars.

Open Access