Lower Leaf Surface Research Articles

Succession and Natural Occurrence of Saprobic Fungi on Leaves ofMagnolia liliiferain a Tropical Forest

Leaves of Magnolia liliifera were selected to evaluate fungal diversity, and succession of fungi during leaf decomposition, and the effect of baiting on fungal diversity. The leaf samples were from Doi Suthep-Pui National Park, Chiang Mai, Thailand. Twenty-three taxa were identified on senescent leaves of M. liliifera during the decay process. Distinct fungal communities were observed with the dominant species on the leaves being different at each succession stage. The most abundant fungal species were Hyponectria sp. 1 (on 60% of leaves), Volutella sp. 1 (60%), Gliocladium sp. 3 (37.1%), Corynespora cassiicola (34.3%), Bionectria ochroleuca (25.7%), Cylindrocladium floridanum (22.8%), Phaeosphaeria sp. (17.1%), Dactylaria longidentata (11.4%) and Lasiosphaeria sp. (11.4%). Leaf bait trials did not show any noticeable effect on fungal diversity when either the upper or lower leaf surface was adjacent to the forest floor. Highest fungal diversity on leaves of M. liliifera occurred between day 4 and 40, with most species being present on day 40. On day 56, leaves were found to be skeletonized, and the fungal communities had decreased in number.

Celtis neglecta (Cannabaceae), a new species from Zhejiang, eastern China

Celtis neglecta Zi L. Chen & X. F. Jin, a new species from Zhejiang, China, is described and illustrated. This new species is most similar to Celtis julianae C. K. Schneid. and C. vandervoetiana C. K. Schneid. It differs from Celtis julianae in having young shoots, petioles, and both mid-ribs and lateral veins of the lower leaf surfaces densely whitish pubescent, and fruit pedicels glabrous or sparsely whitish pubescent. It differs from Celtis vandervoetiana in having young shoots and petioles densely whitish pubescent, and being sparsely whitish pubescent on the upper leaf surfaces, and densely whitish pubescent on both mid-ribs and lateral veins of the lower leaf surfaces. Sequences of the plastid intergenic spacer regions atpB-rbcL and trnL-trnF demonstrate that Celtis julianae and C. vandervoetiana are the closest extant relatives of this new species.

Oviposition site selection by a lepidopteran leafminer in response to heterogeneity of leaf surface conditions: structural traits and microclimates

1. Leafminer larvae are sedentary and make feeding tracks called mines. Their spatial distribution in trees affects their growth and survival through interaction with the heterogeneity of environments, such as leaf traits and microclimate. Lepidopteran leafminers that mine lower leaf surfaces have shown evolutionary radiation, suggesting that lower surfaces improve leafminer performance.2. The lepidopteran multivoltine leafminer Phyllocnistis sp. Zeller (Gracirallidae: Phyllocnistinae) uses the Japanese privet Ligustrum japonicum Thunb. (Oleaceae). It mines only the lower‐surface epidermal layer of primary shoot leaves early in the occurrence season, but once lammas shoots appear, which happens in seasons other than spring, it preferentially uses the lower surface, but also uses the upper surface of the leaves. This study examined whether selection of oviposition sites was associated with the structural traits and microclimate of the leaf surface.3. The shift of oviposition site from primary to lammas shoot leaves followed increasing hardness and epidermal cell wall thickness of primary shoot leaves during leaf development, and mine initiation rates decreased below 20% after oviposition on mature primary shoot leaves. Preference for the lower surface was related to the thinner cuticle. However, the thinner cuticle of the upper surface on lammas shoot leaves allowed Phyllocnistis sp. to expand its mining sites to both surfaces with no decrease in mine initiation and emergence rates.4. Microclimates (leaf surface and mine temperatures) did not differ between upper and lower surfaces, suggesting that microclimate did not affect oviposition site selection by Phyllocnistis sp. These results suggest that the adaptive radiation of lower‐surface mining may have been influenced by the leaf surface characteristics.

IDENTIFICATION OF SECRETORY STRUCTURE, HISTOCHEMISTRY AND PHYTOCHEMICAL COMPOUNDS OF MEDICINAL PLANT Hyptis capitata Jacq.

Hyptis capitata Jacq. (common name: Knobweed or False Ironwort) belongs to Lamiaceae family and is among known traditional medicine. The Anak Dalam Tribe of Jambi Province uses the leaves of H. capitata to cure external and internal wounds. This study was aimed at identifying and analyzing secretory structure, histochemistry and phytochemical content of H. capitata leaves.  The results showed that H. capitata leaves have secretory structures in the form of peltate, capitate and uniseriate glandular trichomes on the upper and lower leaf surfaces, with idioblast cells scattered throughout the leaf mesophyll. Histochemical tests indicated that the peltate trichomes have four head cells, containing alkaloids and terpenoids. This study classified capitate trichomes into two types: 1. type I has one stalk cell and two head cells, all containing  alkaloids, terpenoids and lipophilic compounds; 2. type II has long stalk cells consisting of seven to ten cells with one head cell, all containing alkaloids and terpenoids. Uniseriate glandular trichomes of H. capitata leaves consist of four to eight cells containing alkaloids and terpenoids. The idioblast cells are round-shaped and contain lipophilic compounds. GC-MS analysis showed that H. capitata leaves  contain terpenoid compounds assumed to serve as anti-infective agents, including l-limonene, eugenol, farnesol isomers A, d-nerolidol, hexahydrofarnesol and neophytadiene.

Sooty Mold on Lemon Trees - First Recording from El-Beida City, Libya

Sooty molds are a lineage of follicolous fungi that cover the upper surface of leaves with black mycelia. Sooty molds do not infect plants, but grow on surfaces where honeydew deposits accumulate. Sooty moulds fungi proliferate in abundance on the foliage of lemon subsisting on the honeydew secreted by insects. whiteflies was found in different stages on lower leaf surface. The black color was checked and Alternaria alternata described and reported as new recorded on lemon leaves were infected with white fly in El-Beida, Libya.

Gene expression in response to Cotton Leaf Curl Virus infection in Gossypium hirsutum under variable environmental conditions

Cotton Leaf Curl Disease (CLCuD) is one of the threatening constrains of cotton production in Pakistan for which no adequate remedy is available until now. Local variety of Gossypium hirsutum (FH-142) was grown in field and infected naturally by CLCuV under variable range of temperature and humidity. Plants showed thickening of veins in lower leaf surface at 34?C and 60% relative humidity at 15days post infection (dpi) and curling of leaf margins at 33?C with 58% relative humidity at 30dpi. Remarkable leaf darkening was observed with reduced boll formation at 45dpi at 26?C and 41% relative humidity. Enation developed, severe thickening and curling of leaves intensified and plants showed dwarf growth at 60dpi at 24?C with 52% relative humidity. PCR amplification of Rep associated gene confirmed the presence of CLCuD-associated begomovirus in the infected samples. Quantitative RT-PCR confirmed the amplification and differential expression of a number of pathogen stress responsive genes at different levels of temperature and humidity. This observation predicts that Cotton Leaf Curl Virus (CLCuV) interacts with several host genes that are upregulated to make plants susceptible or suppress other genes to overcome host defense responses.

Three new species of eriophyoid mites (Acariformes, Eriophyoidea) from Lippia alba (Verbenaceae) from Brazil, and remarks on the thorn-like spermathecal process

Abstract Three new vagrant species of eriophyoid mites living on the lower leaf surface of Lippia alba (Mill.) N. E. Brown (Verbenaceae) in the Northeast and Center West Brazil, are described and illustrated. They are: Paraphytoptus serenus sp. nov. and Tegoprionus alobus sp. nov. (both from family Eriophyidae) and Rhynacus lippius sp. nov. (Diptilomiopidae). Detailed anatomy of internal genitalia of the representatives of the three eriophyoid genera (Rhynacus, Paraphytoptus and Tegoprionus) was studied and described for the first time. A new, previously neglected genital structure of eriophyoids, the thorn-like spermathecal process, has been discovered with the aid of confocal laser scanning microscopy. Preliminary analysis indicates that this structure is common for many eriophyid and diptilomiopid species, however it is absent in phytoptid mites. The hypothesis that presence/absence of this process separate contemporary families of Eriophyoidea (Phytoptidae and Eriophyidae+Diptilomiopidae) needs furthe...

Effect of different management tactics on the incidence and movement of red pumpkin beetle, Aulacophora foveicollis on the leaves of sweet gourd, Cucurbita moschata

Incidence and movement of red pumpkin beetle (RPB), Aulacophora foveicollis on the leaves of sweet gourd, Cucurbita moschata were examined against different management tactics. Result revealed that no significant difference was observed on the number of red pumpkin beetle on young leaf among the plots treated with different management tactics. Mature leaf support more number of RPB compared to that of young leaf and the population of RPB gradually increased from 1st to 3rd week. The mean number of RPB per plant was higher on upper leaf surface as compared to lower leaf surface in all the treated plots during early hours of the day before 10 am. The highest number of RPB was observed at 7:00 am on the upper surface and at 1:00 pm on the lower surface of leaves. The percent reduction of RPB over control on both surfaces of leaf was maximum (100 %) by the use of mosquito net barrier (T3) treated plot at 7:00 and 10:00 am, respectively compared to control. The percent reduction of RPB over control at 1:00 pm ranged 94% to 98% on upper leaf surface and at 4:00 pm ranged 94% to 96% on lower surface in T3 treated plot. The minimum acceptable level of percent reduction (above 87%) of RPB population over control was achieved by application of forwatap 4G @ 4g/plant, Nitro 505 EC @ 1 ml/L, hand picking of adult RPB and planting of musk melon as trap crop. The movement of the adult RPB as expressed through the distribution of the beetles on the upper and lower leaf surfaces of sweet gourd during different hours of a day could be helpful for devising the mechanical and chemical control strategies.Jahangirnagar University J. Biol. Sci. 3(2): 73-80, 2014 (December)

Physical Control of Spider Mites Using Ultraviolet-B With Light Reflection Sheets in Greenhouse Strawberries.

Development of spider mite management technology other than chemical control is desired because of the serious development of acaricide resistance worldwide. Recent studies have evidenced the lethal effects of ultraviolet-B (UVB) radiation on spider mites. To develop the technology on how to use UVB irradiation for spider mite control, we tested whether UVB lamp-light reflection sheet (LRS) combinations suppressed the population size of Tetranychus urticae Koch on strawberry in a greenhouse from December to May (2012-2013, 2013-2014) in Japan. We designed four combinations of UVB lamps and LRSs: 1) neither UVB lamps nor LRSs (UV-LRS-); 2) a UVB lamp without an LRS (UV+LRS-; 2012-2013 only); 3) a UVB lamp and a mulch-type LRS (UV+LRSm); and 4) a UVB lamp and a wing-type LRS (UV+LRSw). The number of adult females peaked at 438.0 and 222.0 per plant in UV-LRS- of 2012-2013 and 2013-2014, respectively, and peaked at 191.6 females in UV+LRS- of 2012-2013. In contrast, the peak abundance was 20.9-98.0 females in UV+LRSm, and fewer than 15 females were noted in UV+LRSw over either experimental period. UVB irradiance on lower leaf surfaces was higher in UV+LRSm and UV+LRSw than UV-LRS- and UV+LRS-, and the mite densities were significantly correlated with UVB irradiance on lower leaf surfaces. Consequently, we conclude that the combinations of UVB lamp-LRS have an excellent capacity to control T. urticae on greenhouse strawberry, and that the LRS was an essential component in this technological approach.

Integrative analysis of the West African Ceraceosorus africanus sp. nov. provides insights into the diversity, biogeography, and evolution of the enigmatic Ceraceosorales (Fungi: Ustilaginomycotina)

The order Ceraceosorales (Ustilaginomycotina) currently includes the single genus Ceraceosorus, with one species, Ceraceosorus bombacis, parasitic on Bombax ceiba in India. The diversity, biogeography, evolution, and phylogenetic relationships of this order are still relatively unknown. Here, a second species of Ceraceosorus is described from West Africa as a novel species, Ceraceosorus africanus, infecting Bombax costatum in Benin, Ghana, and Togo. This species produces conspicuous fructifications, similar to corticioid basidiomata when mature, but sorus-like in early stages of ontogenetic development. The fructifications cover much of the leaf surface and resemble leaf blight. This contrasts with the inconspicuous fructifications of C. bombacis comprising small spots scattered over the lower leaf surface that resemble leaf spot. Both species of Ceraceosorus differ in several micromorphological traits, infect different host plant species in widely separated geographical areas, and are separated by a considerable genetic distance in 28S rDNA and RPB2 genes. The distinct corticioid fructification of C. africanus is a unique morphological trait within the Ustilaginomycotina. Molecular phylogenetic analyses of a single gene dataset (D1/D2 28S rDNA) supported the monophyly of the two Ceraceosorus species and the Ceraceosorales and their placement within the Ustilaginomycotina. Molecular phylogenetic analyses of a multigene dataset (18S/5.8S/28S rDNA/RPB2/TEF1) revealed Exobasidium rhododendri (Exobasidiales) as the closest relative of Ceraceosorus, both clustering together with Entyloma calendulae (Entylomatales), indicating affinities to the Exobasidiomycetes. This phylogenetic placement is in agreement with ultrastructural characteristics (presence of local interaction zone and interaction apparatus) reported for the Ceraceosorales, Entylomatales, and Exobasidiales.

Potential aposematism in an insular tree species: are signals dishonest early in ontogeny?

Recent investigations have suggested that some plants are aposematic. Our understanding of how aposematism varies through plant ontogeny, however, is incomplete. Furthermore, the potential for lower leaf surfaces to signal to vertebrate herbivores that are viewing leaves from below has not been investigated. Here, we investigate ontogenetic changes in leaf colour in Pseudopanax crassifolius (Araliaceae), a tree species that is endemic to New Zealand. We demonstrate that P. crassifolius produces lateral leaf spines that peak in size during the sapling stage of development. Spots of brightly coloured tissues on the upper leaf surfaces may be warning signals. The intensity of these signals, however, peaked at the seedling stage, providing a dishonest signal of defence. Conversely, signals on lower leaf surfaces peaked in the sapling stage, providing an honest defensive signal later in ontogeny. Lateral leaf spines and all potential warning colours were absent in adults, after they grow above the reach of the largest known native megaherbivores (moa – Aves: Dinornithiformes). Overall, these results suggest that aposematism may vary predictably through plant ontogeny in response to the changing perspective of herbivores as plants grow vertically.

Puccinia jogashimensis에 의한 갯기름나물 녹병

During July to November 2014, severe rust infection was consistently found on Peucedanum japonicum growing farm in Yeosu, Korea. The rust was observed mainly on lower leaf surfaces. Symptoms of typical plants included yellow-orange rust pustules were observed on the petiole and leaf surface with small yellowish to chlorotic lesions on the upper surface. No symptom was observed on flowers. Uredinia were occurred amphigenous on leaf surface, and occasionally caulicolous, scattered or loosely aggregate, rounded to oblong, 0.4 to 4 mm in diameter, covered by epidermis, then naked, surrounded by ruptured epidermis, pulverulent, and brown. Urediniospores were ovate-ellipsoid, ellipsoid or subglobose, light brown, 20 to 45 ×15 to 35 mm, walls 2 to 4 mm thick. The resulting sequences were deposited in GenBank with accession No. KT778808, KT778809, and KT778810, respectively. Since this was the first accession of 28S sequence Puccinia jogashimensis, there was no exact match in GenBank nucleotide database. On the basis of the morphological characteristics and phylogenetic analyses of 28S rDNA, the fungus was identified as P. jogashimensis. To our knowledge, this is the first confirmed report on the occurrence of P. jogashimensis on P. japonicum in Korea.

The physiology of Curcuma alismatifolia Gagnep. as a basis for the improvement of ornamental production

Distribution and morphology Curcuma is one of the largest genera in the Zingiberaceae family. This genus is in the tribe Zingibereae, which is widely distributed in tropical Asia from India to South China, Southeast Asia, Papua New Guinea and Northern Australia. Thailand seems to be one of the areas richest in this genus (Larsen and Larsen, 2006; Sirirugsa et al., 2007). Approximately 38 species of Curcuma are now found in Thailand, separated into 5 groups, i.e., 1) the “Alismatifolia” group of eight species, C. alismatifolia, C. gracillima, C. harmandii, C. parviflora, C. rhabdota, C. sparganiifolia and two new species, found in the northeastern and eastern region; 2) the “Cochinchinensis” group of two species, C. cochinchinensis and C. pierreana, distributed in the north, southwest and eastern regions; 3) the “Ecomata” group of seven species, C. bicolor, C. ecomata, C. flaviflora, C. glans, C. singularis, C. stenochila and one new species, distributed in the northern, northeastern, eastern and southeastern regions; 4) the “Longa” group of thirteen species, C. aeruginosa, C. amada, C. angustifolia, C. aromatic, C. comosa, C. latifolia, C. leucorrhiza, C. longa, C. mangga, C. rubescens, C. viridiflora, C. zanthorrhiza and C. zedoaria, found widely in the north; and 5) the “Petiolata” group of eight species, C. aurantiaca, C. petiolata, C. roscoeana, C. rubrobracteata and four new species, found from the north to the peninsula along the western ranges (Sirirugsa et al., 2007). Unlike C. longa (tumeric), C. zedoaria, C. aromatic, etc., which are species generally used as medicinal plants (Sabu and Skornickova, 2003), C. alismatifolia Gagnep. is widely cultivated as an ornamental Curcuma for cut flowers and potted plants because the attractive inflorescence has a pink coma bract, called Siam Tulip or Patumma, with a long vase life (Figure 1). This flower clone was first selected by Dr. Pisit Woraurai from Chiang Mai University, and the famous selected clone called ‘Chiangmai Pink’ was introduced as an ornamental plant in early 1980, and nowadays is wellknown in the world market (Woraurai, 1991; Department of Agricultural Extension, 1995; Wannakrairot, 1997). The aboveground organs consisted of leaves and inflorescences. There are two types of leaves, sheath leaves are former sprouting with short and thick leaf blade and followed by foliage leaves with elliptic shape, deep green and reddish median vein. Stomata is mostly tetracyctic type, however, pentacytic and hexacytic types were found in both upper and lower surfaces. Guard cells are kidney shape and the cell size in the adaxial is longer than the abaxial site. Stomatal density in the abaxial site was about 1,000–1,200 stomata mm-2 which was higher than in adaxial site (400–500 stomata mm-2). The cuticle layer of upper leaf surface is about 10–12 μm thick and thicker than the lower leaf surface (13–15 μm thick) (Anuwong et al., 2014b). Underground organs consist of two parts, i.e., the underground stem called a stubbed German Society for Horticultural Science

Jaffrea, a new genus of Rhamnaceae endemic to New Caledonia, with notes on Alphitonia and Emmenosperma

Molecular phylogenetic and morphological data show that two species of Rhamnaceae endemic to New Caledonia, Alphitonia xerocarpa and A. erubescens, are misplaced. They form a clade that is sister to Emmenosperma, and they differ from Alphitonia s.s. in their indumentum, venation, lower leaf surface, flowers, fruits and seeds. Although morphologically closer to Emmenosperma, both their flowers and fruits are distinct from those of Emmenosperma s.s., and so a new genus, Jaffrea H. C. Hopkins & Pillon, is described to accommodate them, and the combinations Jaffrea xerocarpa (Baill.) H. C. Hopkins & Pillon and Jaffrea erubescens (Baill.) H. C. Hopkins & Pillon are published. Members of this new genus have a conical hypanthium, petals somewhat incurved at anthesis, a thick disc that is either ± lumpy or annular but not or only partly covering the semi-inferior ovary, and fruits that are ovoid-ellipsoid, strongly beaked and tardily dehiscent. As in Emmenosperma and most species of Alphitonia, the seeds in Jaffrea can remain attached to the base of the fruit after most of the pericarp has fallen. Alphitonia is now represented in New Caledonia by a single species, A. neocaledonica, and its nomenclature and types are reviewed. The generic description of Alphitonia is amended to include the unique fruits of the New Guinean endemic A. macrocarpa, which are much larger than those of its congeners, strongly beaked, lacking a mealy endocarp, and with seeds that fall before the persistent valves. Relationships within Emmenosperma s.l., especially the affinities of E. papuanum and E. micropetalum, require further investigation.

Making pore choices: repeated regime shifts in stomatal ratio.

Ecologically important traits do not evolve without limits. Instead, evolution is constrained by the set of available and viable phenotypes. In particular, natural selection may only favour a narrow range of adaptive optima constrained within selective regimes. Here, I integrate data with theory to test whether selection explains phenotypic constraint. A global database of 599 plant species from 94 families shows that stomatal ratio, a trait affecting photosynthesis and defence against pathogens, is highly constrained. Most plants have their stomata on the lower leaf surface (hypostomy), but species with half their stomata on each surface (amphistomy) form a distinct mode in the trait distribution. A model based on a trade-off between maximizing photosynthesis and a fitness cost of upper stomata predicts a limited number of adaptive solutions, leading to a multimodal trait distribution. Phylogenetic comparisons show that amphistomy is the most common among fast-growing species, supporting the view that CO2 diffusion is under strong selection. These results indicate that selective optima stay within a relatively stable set of selective regimes over macroevolutionary time.

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:HyphenationZone>21</w:HyphenationZone> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument></xml><![endif]-->A new species and new records of Dorstenia (Moraceae, Dorstenieae) from Rwanda, East Africa<!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles></xml><![endif]--><!--[if gte mso 10]><style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Normale Tabelle"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt;

The new species Dorstenia marijanmatokii from Rwanda is described. It differs from Dorstenia nyungwensis in the discoid and entirely purple receptacle with shorter primary appendages and more numerous and irregular secondary appendages, and the densely tomentose lower leaf surface with purple venation. First records of Dorstenia brownii and D. psilurus from Rwanda and a key to the species of Dorstenia for Rwanda are provided.

Oviposition Site Selection of the Codling Moth (Lepidoptera: Tortricidae) and its Consequences for Egg and Neonate Performance.

The codling moth Cydia pomonella (L.) is a worldwide pest of pome fruit. A better understanding of oviposition site selection by this insect would help management of this pest in orchards. Oviposition site selection of codling moth was assessed by manipulative experiments and field survey. In addition, the temperatures of different sites were recorded. Neonate infestation and egg hatching were tested to evaluate the consequences of oviposition site selection. The percentage of eggs laid on the shady side of apple clusters was significantly higher than on the sunny side. How.ever, this was not influenced by leaf surface turning. Percentage of eggs on upper and lower leaf surfaces was significantly influenced by leaf surface turning. Percentage of eggs on the lower leaf surface was significantly higher than turned lower leaf surface (∼41.1% higher) and significantly higher (∼35.5%) on the turned upper leaf surface on than upper leaf surfaces. There was no significant difference in neonate infestation between leaves and fruit, as well as between the upper and lower leaf surfaces. Number of eggs hatching on the shady side of clusters was significantly higher than on the sunny side (56.3% higher). In both the manipulative experiment and field survey, codling moths did not choose the sites with the highest mean temperature, but chose sites suitable for egg development and hatching. This indicates that in the field codling moth, oviposition site selection is not strictly thermophilous, but they look for the lower leaf surface on the shady side, which benefits the offspring.

Efficacy of fungicides against powdery mildew on watermelon caused by Podosphaera xanthii

Powdery mildew caused by Podosphaera xanthii has affected watermelon in the southeastern United States since the late 1990's. Because this fungus has become resistant to fungicides in FRAC Groups 1 and 11, fungicides in FRAC Groups 3, 7, 9, 12, 13, and U6 were tested on seedless watermelon for their ability to reduce powdery mildew on foliage and prevent yield loss. Nine powdery mildew-specific fungicides were applied three times in alternation with chlorothalonil, which was applied three times in 2013 and four times in 2014. Control treatments included water and chlorothalonil applied every other week. In both years, four fungicide treatments, chlorothalonil alternated with triflumizole, fluopyram + tebuconazole, quinoxyfen, or both cyflufenamid and quinoxyfen reduced leaf area covered with powdery mildew compared to both control treatments. Chlorothalonil alternated with cyflufenamid and quinoxyfen was significantly more effective on lower leaf surfaces than all other treatments. Chlorothalonil alternated with tebuconazole did not differ from chlorothalonil applied every other week. All 10 fungicide treatments increased the number and weight of marketable-sized fruit in both years compared to the water control treatment. Fungicide active ingredients in FRAC Groups 3, 7, 13, and U6 consistently reduced the severity of powdery mildew on seedless watermelon.

Citrus Bacterial Canker Pustules Are Associated With Leafminer Galleries IN IRAN

Citrus bacterial canker is one of the most destructive diseases of citrus in southern Iran. During 2000-2001 and 2005-2006, this disease became endemic showing a reduced severity. This was mainly due to the unfavorable climatic conditions, i.e. low rainfall during the previous years in particular. Control measures included pruning of symptomatic shoots and the use of copper sprays. In Rudan (Hormuzgan province), citrus pustules are usually observed on the lower leaf surface alongside the galleries caused by Phyllocnistis citrella. Bacteria were isolated from these pustules and identified as Xanthomonas citri pv. citri A (Xac) based on biochemical and physiological characteristics (Gram and oxidase reactions, nitrate reduction, urease, hydrolysis of aesculin, casein, gelatin, starch, Tween, sodium chloride tolerance, litmus milk, H2S generation from cysteine and phosphatase, xanthomonadin production, carbohydrate utilization); differential phenotypic features such as bacterial mass colour on Ayer medium containing L-proline, utilization of glycogen, maltose, dextrin, starch (Mohammadi et al., 2001); broad pathogenicity range on inoculated hosts including Mexican lime, unshu tangerine, sour orange, grapefruit and sweet orange. Larval leafminer damage results in elevated incidence and severity of citrus bacterial canker disease (Belasque et al., 2005). Since Ph. citrella is potentially capable of disseminating Xac, thus facilitating canker infection, it is suggested that controlling this pest may result in preventing Xac outbreaks in citrus groves. The association of bacterial canker pustules with leafminer tunnels has previously been reported from North Yemen and India (Cook, 1988; Belasque et al., 2005) but not in Iran, this constituting the first record.

First Report of Peronospora belbahrii on Sweet Basil in Baja California Sur, México

AbstractIn Baja California Sur, Mexico, a foliar disease occurred on sweet basil which seriously affected its quality and yield. The most common symptoms were yellowing and necrosis on leaves, caused by a downy mycelium growth on the lower leaf surface. Symptomatic leaves from two sampling sites were collected for morphological studies and molecular analysis of pathogen DNA. Based on morphological characteristics (sporangiophore size of 240–530 × 7–11 μm, branches of 5–8 order and a sporangia size of 27–31 × 21–25 μm) and molecular analysis (the GenBank blast of the PCR assays showed unique rDNA sequence data with 99% similarity to P. belbahrii), the pathogen was identified as Peronospora belbahrii, the causal agent of basil downy mildew. This is the first report of P. belbahrii affecting sweet basil in Mexico.