Reconsidering Leaf Wetness Duration Determination for Plant Disease Management

Rowlandson, Tracy; Gleason, Mark L.; Sentelhas, Paulo César; Gillespie, T. J.; Thomas, Carla S.; Hornbuckle, B. K.

doi:10.1094/pdis-05-14-0529-fe

Cited by 137 publications

(102 citation statements)

References 49 publications

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“…The above considerations aside, the duration of leaf wetness is generally recognised as an important factor in the development and outbreak of plant diseases because many phytopathogens require a layer of free water for successful infection (Cook, ; Huber & Gillespie, ; Bradley, Gilbert, & Parker, ; Rowlandson et al ., ). The infection efficiencies of pathogens on wet leaves typically increase sigmoidally over time (Spotts, ; Gross et al ., ).…”

Section: Previous Hypotheses Concerning the Function Of Foliar Nyctinmentioning

confidence: 97%

The functions of foliar nyctinasty: a review and hypothesis

Minorsky

2018

Biological Reviews

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Foliar nyctinasty is a plant behaviour characterised by a pronounced daily oscillation in leaf orientation. During the day, the blades of nyctinastic plant leaves (or leaflets) assume a more or less horizontal position that optimises their ability to capture sunlight for photosynthesis. At night, the positions that the leaf blades assume, regardless of whether they arise by rising, falling or twisting, are essentially vertical. Among the ideas put forth to explain the raison d'être of foliar nyctinasty are that it: (i) improves the temperature relations of plants; (ii) helps remove surface water from foliage; (iii) prevents the disruption of photoperiodism by moonlight; and (iv) directly discourages insect herbivory. After discussing these previous hypotheses, a novel tritrophic hypothesis is introduced that proposes that foliar nyctinasty constitutes an indirect plant defence against nocturnal herbivores. It is suggested that the reduction in physical clutter that follows from nocturnal leaf closure may increase the foraging success of many types of animals that prey upon or parasitise herbivores. Predators and parasitoids generally use some combination of visual, auditory or olfactory cues to detect prey. In terrestrial environments, it is hypothesised that the vertical orientation of the blades of nyctinastic plants at night would be especially beneficial to flying nocturnal predators (e.g. bats and owls) and parasitoids whose modus operandi is death from above. The movements of prey beneath a plant with vertically oriented foliage would be visually more obvious to gleaning or swooping predators under nocturnal or crepuscular conditions. Such predators could also detect sounds made by prey better without baffling layers of foliage overhead to damp and disperse the signal. Moreover, any volatiles released by the prey would diffuse more directly to the awaiting olfactory apparatus of the predators or parasitoids. In addition to facilitating the demise of herbivores by carnivores and parasitoids, foliar nyctinasty, much like the enhanced illumination of the full moon, may mitigate feeding by nocturnal herbivores by altering their foraging behaviour. Foliar nyctinasty could also provide a competitive advantage by encouraging herbivores, seeking more cover, to forage on or around non-nyctinastic species. As an added advantage, foliar nyctinasty, by decreasing the temperature between plants through its effects on re-radiation, may slow certain types of ectothermic herbivores making them more vulnerable to predation. Foliar nyctinasty also may not solely be a behavioural adaptation against folivores; by discouraging foraging by granivores, the inclusive fitness of nyctinastic plants may be increased.

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Section: Previous Hypotheses Concerning the Function Of Foliar Nyctinmentioning

confidence: 97%

The functions of foliar nyctinasty: a review and hypothesis

Minorsky

2018

Biological Reviews

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“…There is currently no single meteorological definition of leaf wetting, and research characterizing patterns of canopy wetness has adopted three basic approaches. These approaches are: (1) the direct measure of leaf wetness via electronic sensing grids that change resistance when exposed to water on their surface (Klemm et al, 2002); (2) empirical models based on proxies, such as precipitation and relative humidity (Sentelhas et al, 2008); and (3) physical energy balance models, such as Penman-Monteith (Fritschen & Doraiswamy 1973;Asdak et al, 1998), applied to determine the condensation and evaporation of water on/from leaf surfaces (Kalthoff et al, 2006;Rowlandson et al, 2015). Generally, these lead to descriptions of leaf wetness focused on the duration (e.g.…”

Section: How Often Are Leaves Wet?mentioning

confidence: 99%

“…However, over longer time scales, wetting events could enhance pathogen establishment or leach leaf nutrients, and result in leaf necrosis and the loss of leaves, flowers or fruits that ultimately impact fitness. Alternatively, leaf wetting could lead to novel and potentially important interactions among particular types of effects, whereby wet deposition alters leaf surface properties in ways that impact the capacity for pathogens to establish (Percy & Baker, 1988;Rowlandson et al, 2015).…”

Section: Reproductionmentioning

confidence: 99%

The value of wet leaves

2018

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Contents Summary 1156 I. Introduction 1156 II. How often are leaves wet? 1157 III. The costs of leaf wetting 1157 IV. The real and potential benefits of leaf wetting 1161 V. Wet leaves: costs, benefits and tradeoffs in a changing world 1165 Acknowledgements 1166 References 1166 SUMMARY: An often-overlooked feature of all plants is that their leaf surfaces are wet for significant periods over their lifetimes. Leaf wetting has a number of direct and indirect effects on plant function from the scale of the leaf to that of the ecosystem. The costs of leaf wetting for plant function, such as the growth of pathogens and the leaching of nutrients, have long been recognized. However, an emerging body of research has also begun to demonstrate some very clear benefits. For instance, leaf wetting can improve plant-water relations and lead to increased photosynthesis. Leaf wetting may also lead to synergistic effects on plant function, such as when leaf water potential improvements lead to enhanced growth that does not occur when plant leaves are dry. We identify important reasons why leaf wetting can be critical for plant sciences to not only acknowledge, but also directly address, in future research. To do so, we provide a framework for the consideration of the relative balance of the various costs and benefits resulting from leaf wetting, as well as how this balance may be expected to change given projected scenarios of global climate change in the future.

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“…Leaf wetting further affects numerous ecological processes, such as photosynthesis rate (Hanba et al 2004), pathogen infection (Rowlandson et al 2015) or absorption and removal of pollutants (Neinhuis and Barthlott 1997). Plant ability to repel water from the leaf surface can be termed as its hydrophobicity and can be comprehensively described by measuring the contact angle (CA) between a water droplet and the leaf surface (Bradley et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Variation in Leaf Surface Hydrophobicity of Wetland Plants: the Role of Plant Traits in Water Retention

et al. 2017

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Leaf surface wetness has numerous physiological and ecological consequences, and the morphological structures on the leaf surface can affect its extent and duration, contributing to interception rates in the scale of the whole ecosystem. Wetland plants have developed morphological adaptations to high water level allowing them to avoid water excess. Droplet contact angle and surface free energy are measurable parameters which relate to how the plant influences water usage and redistribution. We analysed patterns of contact angle and the surface free energy of the adaxial and abaxial surface of 10 wetland plant species and related them to the optimal habitat conditions and functional traits of the plants. Despite the consistent environment of these plants, we found them to vary greatly in terms of leaf surface wettability and surface free energy, with contact angles ranging from 75 to 169°and surface free energy, from 1.32 to 30.38 mJ/m 2 . Canopy height and leaf longevity were significantly correlated to leaf wettability, whilst SLA (Specific Leaf Area) and leaf shape were not related to hydrophobicity. Investigating adaptations of wetland plants to their environment showed that including wettability and surface free energy in combination with other plant traits improves our understanding of water plant-soil-water interactions in wetland habitats.

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Reconsidering Leaf Wetness Duration Determination for Plant Disease Management

Cited by 137 publications

References 49 publications

The functions of foliar nyctinasty: a review and hypothesis

The functions of foliar nyctinasty: a review and hypothesis

The value of wet leaves

Variation in Leaf Surface Hydrophobicity of Wetland Plants: the Role of Plant Traits in Water Retention

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