Influence of leaf surface micromorphology, wax content, and surfactant on primisulfuron droplet spread on barnyardgrass (Echinochloa crus-galli) and green foxtail (Setaria viridis)

Weed Science ◽  
2006 ◽  
Vol 54 (4) ◽  
pp. 627-633 ◽  
Author(s):  
Debanjan Sanyal ◽  
Prasanta C. Bhowmik ◽  
Krishna N. Reddy

Laboratory studies were conducted to examine the leaf surface, epicuticular wax content, and spread area of primisulfuron spray droplet with and without surfactant on leaf surface of barnyardgrass and green foxtail. Adaxial and abaxial leaf surfaces were examined using scanning electron microscopy and leaf wax was extracted and quantified. The spread of 1-μl droplets of distilled water, primisulfuron solution (without surfactant), primisulfuron solution with a nonionic low foam wetter/spreader adjuvant (0.25% v/v), and with an organosilicone wetting agent (0.1% v/v) was determined on the adaxial leaf surfaces of each of the weed species. Stomata and trichomes were present on adaxial and abaxial leaf surfaces in both species. Green foxtail had more stomata per unit area on the adaxial as compared to the abaxial leaf surface. Barnyardgrass had more stomata on the abaxial than on the adaxial leaf surface. There was no significant variation in the number of trichomes per unit leaf area of green foxtail, and the number of prickles per unit area of leaf was significantly higher in adaxial than the abaxial leaf surface, in both young and old leaves. In barnyardgrass, there were more trichomes on abaxial than adaxial leaf surface. The mean value of the wax content per unit of leaf area in barnyardgrass and green foxtail was 35.9 μg cm−2and 19.1 μg cm−2, respectively. On both species primisulfuron with a nonionic surfactant had more spread area than that without a surfactant, and the spread was even greater with organosilicone wetting agent. The spread area of primisulfuron droplet was higher on the leaf surface of barnyardgrass than on green foxtail when surfactant was added.

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 469-475 ◽  
Author(s):  
W. Mack Thompson ◽  
Scott J. Nissen ◽  
Robert A. Masters

Laboratory experiments were conducted to identify adjuvants that improve absorption of imazethapyr, 2,4-D amine, and picloram by leafy spurge. Adjuvants (0.25% v/v) included crop oil concentrate (COC), methylated seed oil (MSO), nonionic surfactant (NIS), organosilicones (Silwet L-77®, Sylgard® 309, Silwet® 408), 3:1 mixtures of acetylinic diol ethoxylates (ADE40, ADE65, ADE85) with Silwet L-77, ammonium sulfate (2.5 kg ha−1), and 28% urea ammonium nitrate (UAN, 2.5% v/v). Adjuvants were combined with14C-herbicide and commercially formulated herbicide product. Leaves were harvested 2 DAT, rinsed with 10% aqueous methanol to remove surface deposits of herbicide, and dipped in 9:1 hexane:acetone to solubilize cuticular waxes. Imazethapyr absorption increased by 38 to 68% when UAN was combined with COC, NIS, or MSO. Total absorption of imazethapyr plus COC, MSO, or NIS exceeded 86% 2 DAT when UAN was added. Urea ammonium nitrate reduced the amount of imazethapyr associated with the cuticular wax by 2.0%. Imazethapyr absorption was similar on both the abaxial and adaxial leaf surface when UAN was not added; however, 12% more imazethapyr was absorbed from the abaxial leaf surface than from the adaxial leaf surface when UAN was combined with Sylgard 309. Uptake of 2,4-D ranged from 54 to 78% and was greatest with Silwet 408 and 3:1 mixture of ADE40: Silwet L-77. Picloram absorption ranged from 3 to 19%. Buffering picloram treatment solutions to pH 7 and including 2.5 kg ha-1ammonium sulfate increased picloram absorption to 37%.


Phytotaxa ◽  
2015 ◽  
Vol 238 (1) ◽  
pp. 82
Author(s):  
Guilherme Medeiros Antar ◽  
BENOÎT LOEUILLE

Vernonia monocephala subsp. irwinii is a member of the genus Lessingianthus and is hereby transferred to that genus with a new status and a new name, L. semirii. It differs from L. monocephalus by its subsessile to petiolate (vs. sessile) leaves, largely attenuate (vs. rounded to attenuate) leaf bases, adaxial leaf surfaces drying black (vs. greenish), tomentose to velutinous (vs. villous) abaxial leaf surface and stem indument, and number of florets per head (up to 120 vs. up to 210). Both species are native to provinces of the Cerrado Domain, but they do not occur sympatrically: L. semirii is restricted to the North-eastern floristic province (Bahia, Maranhão, Tocantins and Pará states) and northern portion of the Central-western floristic province (Mato Grosso state), whereas L. monocephalus occurs in Distrito Federal and Goiás states in the Central-western, Central and South-eastern floristic provinces. Lessingianthus semirii is hereby described and illustrated for the first time; a distribution map is provided and affinities of this species are discussed.


2015 ◽  
Vol 87 (2) ◽  
pp. 787-796 ◽  
Author(s):  
JOAQUIM M. DUARTE-ALMEIDA ◽  
MILENE S. CLEMENTE ◽  
ROSANI C.O. ARRUDA ◽  
ANGELA M.S.F. VAZ ◽  
ANTONIO SALATINO

Large elongated glands occur on Cercideae leaf surfaces. Leaves of Bauhinia (55 taxa, 53 species), Cercis (1 species), Phanera (1 species), Piliostigma (2 species), Schnella (19 species) and Tylosema (1 species) were observed to determine location and relative number of glands. They were only observed on the abaxial leaf surface of 42 Bauhinia taxa. The glands were analyzed by light stereomicroscope and scanning electron microscopy. They are large (up to 270 µm long and 115 µm wide) and multicellular, containing lipophilic substances, probably volatile oils. Presence or absence and density of the glands in species of Bauhinia may be useful to determine species delimitation or distinction among infraspecific taxa. Higher density of glands is more common in species from "cerrado" (a savanna ecosystem) and "caatinga" (a semiarid ecosystem from northeast Brazil) areas. Bauhinia species devoid of foliar glands are frequently from humid forests.


Weed Science ◽  
1993 ◽  
Vol 41 (1) ◽  
pp. 87-93 ◽  
Author(s):  
Moritz Knoche ◽  
Martin J. Bukovac

The effect of oxyethylene (OE) chain length of three homologous series of nonionic surfactants (allinol, nonoxynol, octoxynol) on glyphosate uptake was markedly affected by the leaf surface fine-structure of sugarbeet and kohlrabi. Adaxial leaf surfaces of sugarbeet were covered with a layer of amorphous wax, whereas the adaxial surface of kohlrabi leaves was covered with fine crystalline wax. Foliar uptake of glyphosate (1 mM glyphosate, 20 mM glycine, pH 3.2) averaged 4% for sugarbeet without surfactant, but droplets were not retained by kohlrabi leaves in the absence of a surfactant. Glyphosate absorption with octoxynol (9 to 10 OE units, 0.5 g L−1) was rapid initially (0 to 2 h) and leveled off about 2 h after application in both species. Absorption by sugarbeet decreased from 12 to 3% as OE content of octoxynol was increased from 5 to 30 OE units. In contrast, surfactants of intermediate OE content (octoxynol, 16 OE units) induced the greatest uptake (17%) on kohlrabi. Leaf wetting was markedly affected by surfactant and leaf surface. As OE content of octoxynol increased from 5 to 30 OE units, droplet/leaf interface areas of 1-μl droplets decreased from 4 to 3 mm2 on the adaxial leaf surface of sugarbeet and from 61 to 2 mm2 on kohlrabi. Concurrently, the rate of droplet evaporation (1 μl) decreased from 1.0 to 0.7 nl s−1 on sugarbeet and 4.2 to 0.5 nl s−1 on kohlrabi leaves. The effect of OE content on enhancement of glyphosate uptake and wetting characteristics of spray solutions was similar within species for different hydrophobic moieties but differed markedly between species.


Weed Science ◽  
2006 ◽  
Vol 54 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Debanjan Sanyal ◽  
Prasanta C. Bhowmik ◽  
Krishna N. Reddy

Laboratory studies were conducted to examine the leaf surface, epicuticular wax content, and spray droplet behavior on common lambsquarters, common purslane, and velvetleaf. Adaxial and abaxial leaf surfaces were examined using scanning electron microscopy, and leaf wax was extracted and quantified for all three weed species. The spread of 1-μl droplets of distilled water, primisulfuron solution (without surfactant), primisulfuron solution with a nonionic low foam wetter/spreader adjuvant (0.25% v/v), and with an organosilicone wetting agent (0.1% v/v) was determined on the adaxial leaf surfaces of each of the weed species. Glands and trichomes were present on both the adaxial and abaxial leaf surfaces of velvetleaf. Common purslane had neither glands nor trichomes on either side of the leaf. Common lambsquarters did not have any glands or trichomes, but it had globular bladder hairs on both adaxial and abaxial leaf surfaces. Stomata were present on both adaxial and abaxial leaf surfaces in all three weed species. Common purslane had a much lower number of stomata per unit area of leaf as compared with velvetleaf or common lambsquarters. Common lambsquarters had the highest epicuticular wax content on the leaf surface (274.5 μg cm−2), followed by common purslane (153.4 μg cm−2) and velvetleaf (7.4 μg cm−2). There were no significant variations in the spread of the 1-μl droplet of distilled water and primisulfuron (without adjuvant) among the species. Spread of primisulfuron droplets with surfactant was highest on the leaf surface of velvetleaf that had the lowest wax content. Droplet spread was greatest with organosilicone surfactant followed by the nonionic surfactant.


Weed Science ◽  
1974 ◽  
Vol 22 (4) ◽  
pp. 394-401 ◽  
Author(s):  
F. D. Hess ◽  
D. E. Bayer ◽  
R. H. Falk

The distribution pattern of MCPA ([(4-chloro-o-tolyl)oxy] acetic acid) on leaf surfaces of three species was studied using the cathodoluminescence detection mode of a scanning electron microscope. On low-wax-content sugarbeet (Beta vulgarisL.) leaves MCPA concentrated in the depressions over the anticlinal cell walls when applied at high volumes (748 and 374 L/ha). At low volumes (23 L/ha), numerous small deposits of MCPA were randomly distributed over both anticlinal and periclinal walls. These distinct patterns were independent of herbicide concentration. Regardless of spray volumes, MCPA remaining on the waxy leaf surfaces of cabbage (Brassica oleraceaL.) coalesced into small thick deposits. Large spray drops from high application volumes shattered on impact with the stellate hairs of turkey mullein (Eremocarpus setigerusBenth.) resulting in some MCPA reaching the leaf surface. Spray drops from low application volumes did not shatter but lodged on the hairs with very little reaching the leaf surface.


2000 ◽  
Vol 78 (1) ◽  
pp. 34-39
Author(s):  
Luc St-Laurent ◽  
Bernard R Baum ◽  
Koffi Akpagana ◽  
John T Arnason

Leaf trichome morphology and density are described for three species belonging to the genus Trema from West Africa: T. africana (Planch.) Blume, T. orientalis (L.) Blume, and T. nitens (Hook. & Planch.) Blume. Leaves of specimens collected in West Africa were observed using scanning electron microscopy. Unicellular trichome morphology was assessed, and a 3 × 3 two-way contingency table analysis showed dependence between the trichome type and species identity. Density of unicellular and multicellular trichomes on both leaf surfaces as well as the number of cells composing the stalk of multicellular trichomes were measured and subjected to nonparametric analysis of variance. Kruskal-Wallis tests yielded significant results (p < 0.05) among the three species for all characters except unicellular trichome density on the adaxial leaf surface. Wilcoxon two-sample tests showed that all species were different, except for the density of multicellular trichomes on the abaxial leaf surface where densities in T. africana and T. orientalis were not significantly different. The number of cells composing the stalk of multicellular trichomes was significantly different among each species on the adaxial leaf surface, but on the abaxial one, T. africana and T. orientalis exhibited no significant differences. The value of these characters in the discrimination between the three species is discussed.Key words: Trema spp., Ulmaceae, West Africa, leaf trichomes, morphology, density.


2019 ◽  
Vol 14 (1) ◽  
pp. 123
Author(s):  
Paulo Henrique Siqueira Sabino ◽  
Gian Otavio Alves Da Silva ◽  
Adriano Bortolotti Da Silva ◽  
Geraldo Andrade Carvalho

The present study aimed to evaluate the effects of applying fungicides with different sources of copper and of the number of applications on the occurrence of <em>Leucoptera coffeella </em>(Guérin-Menéville &amp; Perrottet, 1842) (Lepidoptera: Lyonetiidae) and on the wax layer on leaves in a coffee plantation. Four applications of fungicides were carried out and the effects on the number of leaves mined by the insect and on the wax content on the leaf surface were evaluated. The copper-based fungicides increased the number of leaves mined by the leaf-miner and reduced the wax content on the coffee leaf surfaces in both periods studied.


HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1217-1221 ◽  
Author(s):  
A.N. Kishaba ◽  
S. Castle ◽  
J.D. McCreight ◽  
P.R. Desjardins

Confined-leaf tests in a greenhouse showed Lagenaria siceraria (Molina) Standley plant introduction (PI) 442369 was as susceptible to sweetpotato whitefly, Bemisia tabaci Gennadius, oviposition as Cucumis melo L., Cucurbita ecuadorensis Cutler and Whitaker, and Cucurbita lundelliana Bailey, whereas L. siceraria accessions PI 419090, PI 419215, PI 432341, and PI 432342 were resistant. Resistance rankings of L. siceraria accessions based on adult counts in greenhouse and field tests were similar. Adult entrapment among trichomes was highest on adaxial leaf surfaces of L. siceraria PI 419090. Abaxial leaf trichome density was 48.7/mm2 on sweetpotato whitefly-resistant L. siceraria PI 432342, 42.1/mm2 on Cucurbita lundelliana PI 540895, and ranged from 51.0 to 85.5/mm2 on Cucurbita ecuadorensis PI 540896. Leaf trichome densities of selected plants of four L. siceraria accessions ranged from 33.0 to 52/mm2 on the abaxial and from 6.3 to 20.8/mm2 on the adaxial surface. Scanning electron micrographs of the abaxial leaf surface, the preferred surface for oviposition, suggest that trichome configuration (density and arrangement of different lengths) could be a factor in reduction of whitefly oviposition on L. siceraria.


2023 ◽  
Vol 83 ◽  
Author(s):  
L. F. Silva ◽  
F. W. S. Silva ◽  
G. L. Demolin-Leite ◽  
M. A. Soares ◽  
P. G. Lemes ◽  
...  

Abstract Acacia auriculiformis A. Cunn. Ex Benth. (Fabaceae), a non-native pioneer species in Brazil with fast growth and rusticity, is used in restoration programs. Our goal was to assess during a 24-month survey the pattern of arthropods (phytophagous insects, bees, spiders, and predator insects) on the leaf surfaces of A. auriculiformis saplings. Fourteen species of phytophagous, two of bees and eleven of predators were most abundant on the adaxial surface. The values of the ecological indexes (abundance, diversity, and species richness) and the rarefaction, and k-dominance curves of phytophagous, bees and arthropod predators were highest on the adaxial leaf surface of A. auriculiformis. The k-dominance and abundance of Aleyrodidae (Hemiptera) (both leaf surfaces), the native stingless bee Tetragonisca angustula Latreille (Hymenoptera: Apidae) (both leaf surfaces) and the ant Brachymyrmex sp. (adaxial surface) and Pheidole sp. (Hymenoptera: Formicidae) (abaxial surface) were the highest between the taxonomic groups of phytophagous, bees, and predators, respectively on A. auriculiformis saplings. The ecological indexes and rarefaction, abundance, and k-dominance curves of phytophagous insects, bees, and predators were highest on the adaxial leaf surface. The preference of phytophagous insects for the adaxial leaf surface is probably due to the lower effort required to move on this surface. Understanding the arthropod preferences between leaf surfaces may help to develop sampling and pest management plans for the most abundant phytophagous insects on A. auriculiformis saplings. Also, knowledge on the preference pattern of bees and predators may be used to favour their conservation.


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