Effect of an organosilicone surfactant on spray drop adhesion and retention by pea (<i>Pisum sativum</i>) leaf surfaces

Powdery mildew occurred widely on faba beans (Vicia faba L.) in Manitoba in 1974. Mycelia, and conidia were abundant on both leaf surfaces. The fungus later developed numerous cleistothecia 99–143 μm in diam, with rigid appendages, 128–286 μm in length, dichotomously branched at their apices and ending in recurved tips. Frequently, appendages were contorted and irregularly branched. Cleistothecia contained 5–8 asci. The fungus produced mildew symptoms on Lathyrus ochroleucus Hook., L. odoratus L., L. latifolius L., and Vicia americana Muhl., but failed to infect Lonicera tatarica L., Pisum sativum L., and Syringa vulgaris L. The fungus was identified as Microsphaera penicillata (Wall. ex Fr.) Lév. var. ludens (Salmon) Cooke on the basis of morphological characters and pathogenicity. Lathyrus spp. are new hosts of the fungus. L. ochroleucus and V. americana may be sources of primary inoculum of the fungus in Manitoba. Erysiphe pisi DC. reported to occur on V. faba was not found on any of the specimens.

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Morphology of Erysiphe pisi on leaves of Pisum sativum

Canadian Journal of Botany ◽

10.1139/b89-415 ◽

1989 ◽

Vol 67 (11) ◽

pp. 3410-3416 ◽

Cited By ~ 18

Author(s):

Richard E. Falloon ◽

Paul W. Sutherland ◽

Ian C. Hallett

Keyword(s):

Electron Microscope ◽

Pisum Sativum ◽

Scanning Electron Microscope ◽

Hyphal Growth ◽

Erysiphe Pisi ◽

Hyphal Branching ◽

Leaf Surfaces ◽

Conidium Germination ◽

Scanning Electron

Morphological details of conidium germination, hyphae, appressoria, conidiophores, and organisation within colonies of Erysiphe pisi on leaves of Pisum sativum were studied in frozen, hydrated specimens with a scanning electron microscope. The pathogen has several adaptations to enable efficient colonisation of host leaf surfaces, including production of several hyphae from each germinated conidium, unidirectional growth of individual hyphae, prolific hyphal branching at obtuse angles to lines of hyphal growth, and rapid and prolific development of appressoria and conidiophores. Hyphal cells on leaf surfaces are specialised to produce either appressoria or conidiophores and hyphal branches.

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Spread of Water and Oil Droplets on Johnsongrass (Sorghum halepense) Leaves

Weed Science ◽

10.1017/s004317450005219x ◽

1993 ◽

Vol 41 (3) ◽

pp. 460-467 ◽

Cited By ~ 12

Author(s):

Chester G. Mcwhorter ◽

Clark Ouzts ◽

James E. Hanks

Keyword(s):

Surface Tension ◽

Weight Loss ◽

Lower Surface ◽

Sorghum Halepense ◽

Oil Droplets ◽

Base Oil ◽

Leaf Surfaces ◽

Sunflower Oils ◽

Paraffinic Oil ◽

Organosilicone Surfactant

Comparative spread of droplets of several different oils and water with different adjuvants on leaf surfaces was investigated. Spread was better on the lower surface of johnsongrass leaves than on upper leaf surfaces with nine of 14 oils studied; two spread best on upper leaf surfaces, and three were equal in spread on both surfaces. Differences in spread coefficients did not appear to be directly related to surface tension, viscosity, or mid-boiling point of the oils. Soybean or cottonseed oils did not spread as well as petroleum oils but methylated soybean and sunflower oils had high spread coefficients on both upper and lower leaf surfaces. All but one petroleum-base oil spread three to four times better on leaf surfaces than on oil-sensitive paper. Water mixtures of an organosilicone surfactant spread much better on water-sensitive paper and on johnsongrass leaves than water with conventional adjuvants, but spread of paraffinic oils exceeded that of any water-adjuvant mixture. Spread coefficients of most petroleum-base oils were better on lower than upper leaf surfaces. Spread usually increased as the age of leaves increased from 14 to 56 d. Water droplets with adjuvant had at least an 86% weight loss after 6 min, but low volatile paraffinic oil droplets had little weight loss 2 d after application.

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Infra-Specific Variation in Wax on Leaf Surfaces

Australian Journal of Biological Sciences ◽

10.1071/bi9650323 ◽

1965 ◽

Vol 18 (2) ◽

pp. 323 ◽

Cited By ~ 78

Author(s):

DM Hall ◽

AI Matus ◽

JA Lamberton ◽

HN Barber

Keyword(s):

Electron Microscope ◽

Light Scattering ◽

Pisum Sativum ◽

Leaf Surface ◽

Chemical Data ◽

Surface Wax ◽

Leaf Surfaces ◽

Specific Variation ◽

Wax Deposits ◽

Cuticular Surface

The structure of the surfaCe wax on green and glaucous variants in Eucalyptus urnigera, Poa colensoi (natural cline forms), Pisum sativum, and BraBsica oleracea (mutants) are described as seen under the electron microscope. Preliminary chemical data are also given. The green forms always possess wax deposits which are either smooth films on the cuticle or consist predominantly of platelets which lie flat on the cuticular surface. In some cases the platelets tend to be arranged in parallel groups. In the glaucous variants, the wax consists predominantly of rods or filaments growing outwards from the leaf surface and presenting many light-scattering surfaces.

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Leaf Surface Morphology of Erythroxylum sp. and Droplet Spread

Weed Science ◽

10.1017/s0043174500084101 ◽

1994 ◽

Vol 42 (1) ◽

pp. 18-26 ◽

Cited By ~ 7

Author(s):

Chester G. McWhorter ◽

Clark Ouzts

Keyword(s):

Surface Morphology ◽

Leaf Surface ◽

Cottonseed Oil ◽

Epidermal Cells ◽

Water Droplets ◽

Leaf Surfaces ◽

Subsidiary Cells ◽

Wax Crystals ◽

Organosilicone Surfactant

Studies were conducted to examine the micromorphology of leaf surfaces of coca and nova plants and to determine which spray diluents provided optimum coverage of leaf surfaces. Adaxial leaf surfaces of both species were covered with a smooth layer of polygonal-shaped epidermal cells which were covered with wax crystals. Abaxial leaf surfaces were composed only of papillae cells and the guard and subsidiary cells surrounding stomata. Abaxial leaf surfaces of both species were also covered with wax crystals. Average wax weights were 28 to 53 μg cm−2. Water droplets containing an organosilicone surfactant at 0.1% by vol spread better on leaf surfaces that did other adjuvants. Droplets of several different petroleum-based oils spread much better on leaf surfaces than either water droplets with adjuvants or droplets of soybean or cottonseed oil.

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