Plant Health 2023



Fixing Dead Patches in Lawns Caused by Petroleum Spills

Damage in lawns caused by petroleum-based spills is very difficult to correct. Yuan et al. (p. 250) report an integrated approach to reestablish turfgrass in dead patches caused by petroleum. They treated damaged areas immediately after the spill with liquid humic amendment or activated charcoal at 0.2 gal/ft2 and nitrate nitrogen at 1 lb/acre. Perennial ryegrass was reseeded at 305 lb/acre and covered with peat pellets at a thickness of 0.375 inch. Using this approach, new turf of acceptable quality was established 6 weeks after diesel and hydraulic fluid spills.

Spectral Analysis Helps to Diagnose Citrus Black Spot Disease

Florida is experiencing early fruit drop and yield loss in citrus due to a recently found fungal disease called citrus black spot (CBS). CBS generates various lesions on the fruit peel, but the most distinguishing symptom is called hard spot, which is a gray spot surrounded by a black margin. Pourreza et al. (p. 254) conducted a spectral analysis to determine the best waveband for detecting CBS lesions using a non-destructive optical sensing method. The proposed method was able to identify CBS with accuracies ranging from 93.3% to 94.6%. These results will be used to build a vision-based sensor for in-field diagnosis.

Scion Leaf Removal Increases Grafting Success in Tomato

The utilization of grafted tomato plants is gaining momentum in the U.S., particularly for high-tunnel and/or small-acreage farmers. As a result, growers are interested in simple propagation techniques that can be used on the farm to increase grafting success. Removing scion leaf and/or shoot tissue in order to reduce transpiration and subsequent water stress could minimize the intensive post-grafting management required. Masterson et al. (p. 261) found that leaf removal increased grafting success from 78% to 84% compared to the standard splice grafting method. Removal of the entire meristem (shoot removal) did not penalize grafting success.

Planting Time and Flurprimidol Affect Growth of Lachenalia

Lachenalia has the potential to become an extremely attractive pot plant or cut flower given its variations in flower color and longevity. Kapczyńska and Malik (p. 293) soaked lachenalia bulbs (15 and 30 mg·L-1) or sprayed leaves (15, 30, 45, and 60 mg·L-1) of ‘Rupert’ and ‘Ronina’ lachenalia planted from November to February. Soaking the bulbs in flurprimidol at 30 mg·L-1 appeared to be the most effective in controlling lachenalia growth. The highest quality of potted lachenalia was obtained by planting bulbs in January and February.

Saline Irrigation of Three Native Landscape Plant Species

Saline water has the potential to be used as an irrigation source, reducing the demand for potable water. LeCompte et al. (p. 309) observed that although saline irrigation may reduce plant size, there is not necessarily a reduction in plant visual quality for some species. Muhly grass and small anise tree were found to be tolerant of saline irrigation, while sweetspire was mostly intolerant. Weekly irrigation with non-saline water may be an effective management strategy to alleviate plant stress and prevent salt buildup in the root zone.

Colorants Enhance Aesthetics of Dormant Zoysiagrass

Zoysiagrass is a warm-season turfgrass species that requires less water and fewer cultural inputs than cool-season grasses. However, its widespread use by homeowners in the transition zone may be limited because of its extended duration of brown color during dormancy. Braun et al. (p. 314) evaluated three colorants, each applied at three application volumes to dormant zoysiagrass. Zoysiagrass color was enhanced by using colorants, and the duration of acceptable color increased with application volume. Homeowners may be more amenable to the use of zoysiagrass if colorants are used to enhance the aesthetic appeal of dormant turf.

Moringa Leaf Extract and Cytokinins Increase Cherry Tomato Yield

Moringa leaf extract (MLE) and trans-zeatin (t-Z) applied to the foliage or roots of cherry tomato plants increased plant biomass, height, vegetative and floral shoot number, flower number, and yield, and increased the nutritional quality and putative health benefits of the fruit compared to untreated control plants. 6-Benzyladenine was less effective. Analysis of moringa leaves identified significant pools of cytokinin ribosides. The results of this preliminary research conducted by Basra and Lovatt (p. 327) justify further research to develop the use of MLE and cytokinins in commercial tomato production, specifically MLE as a cytokinin alternative for organic production.

Shading Reduces Heat Stress in Tomato and Pepper in West Texas

Shading is a common practice in Spain and Mediterranean countries for reducing solar radiation and heat stress. Masabni et al. (p. 344) conducted a study in west Texas to assess the efficacy of shading by growing tomato and chili pepper under full sun, 50% shading, or 70% shading. Results indicated that 50% shading reduced heat stress for both crops and had similar ripe fruit yield compared to full sun, while 70% shading reduced yield for both crops. They concluded that 50% shading benefits vegetable production in west Texas; however, a shading percentage below 50% may be better.

Creativity in the Horticulture Classroom

Creativity is considered important for success in most disciplines, yet instructors may not intentionally promote creative exercises in the horticulture classroom, or be aware of how current practices help nurture creative problem solving. Classroom activities that promote creative expression, examples of specific student behaviors that create an environment fostering creativity, and approaches to assessment were identified from a survey of courses in Cornell University’s horticulture curriculum (Pritts and Eames-Sheavly, p. 358). From the quantity of submitted examples and comments from instructors, it is clear that classroom activities that promote creative thought are prevalent, but often not recognized as such by instructors.

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