Lower Leaf Surface Research Articles

Kermadecia brinoniae (Proteaceae: Macadamieae), a new species from New Caledonia previously confused with K. elliptica

Hopkins, H.C.F. & Y. Pillon (2019). Kermadecia brinoniae (Proteaceae: Macadamieae), a new species from New Caledonia previously confused with K. elliptica. In English, English and French abstracts. Candollea 74: 85–92. DOI: http://dx.doi.org/10.15553/c2019v741a9Kermadecia brinoniae H.C. Hopkins & Pillon (Proteaceae), which occurs in southern New Caledonia, principally on ultramafic substrates, is described and illustrated. Material of this species was previously included in Kermadecia elliptica Brongn. & Gris. An amended description is given for the latter and a lectotype designated. These two species differ in the prominence of the venation on the lower leaf surface and in their ecology. Kermadecia brinoniae, like other species of Proteaceae growing on ultramafic substrates of New Caledonia, has a relatively high content of manganese in its leaves. A revised key to the species of Kermadecia Brongn. & Gris is provided as well as notes on the morphology of the pollen presenter.

Avian UV vision enhances leaf surface contrasts in forest environments

UV vision is prevalent, but we know little about its utility in common general tasks, as in resolving habitat structure. Here we visualize vegetated habitats using a multispectral camera with channels mimicking bird photoreceptor sensitivities across the UV-visible spectrum. We find that the contrast between upper and lower leaf surfaces is higher in a UV channel than in any visible channel, and that this makes leaf position and orientation stand out clearly. This was unexpected since both leaf surfaces reflect similarly small proportions (1–2%) of incident UV light. The strong UV-contrast can be explained by downwelling light being brighter than upwelling, and leaves transmitting < 0.06% of incident UV light. We also find that mirror-like specular reflections of the sky and overlying canopy, from the waxy leaf cuticle, often dwarf diffuse reflections. Specular reflections shift leaf color, such that maximum leaf-contrast is seen at short UV wavelengths under open canopies, and at long UV wavelengths under closed canopies.

Detection of Huanglongbing (citrus greening) based on hyperspectral image analysis and PCR

Huanglongbing (HLB, citrus greening) is one of the most serious quarantine diseases of citrus worldwide. To monitor in real-time, recognize diseased trees, and efficiently prevent and control HLB disease in citrus, it is necessary to develop a rapid diagnostic method to detect HLB infected plants without symptoms. This study used Newhall navel orange plants as the research subject, and collected normal color leaf samples and chlorotic leaf samples from a healthy orchard and an HLB-infected orchard, respectively. First, hyperspectral data of the upper and lower leaf surfaces were obtained, and then the polymerase chain reaction (PCR) was used to detect the HLB bacterium in each leaf. The PCR test results showed that all samples from the healthy orchard were negative, and a portion of the samples from the infected orchard were positive. According to these results, the leaf samples from the orchards were divided into disease-free leaves and HLB-positive leaves, and the least squares support vector machine recognition model was established based on the leaf hyperspectral reflectance. The effect on the model of the spectra obtained from the upper and lower leaf surfaces was investigated and different pretreatment methods were compared and analyzed. It was observed that the HLB recognition rate values of the calibration and validation sets based on upper leaf surface spectra under 9-point smoothing pretreatment were 100% and 92.5%, respectively. The recognition rate values based on lower leaf surface spectra under the second-order derivative pretreatment were also 100% and 92.5%, respectively. Both upper and lower leaf surface spectra were available for recognition of HLB-infected leaves, and the HLB PCR-positive leaves could be distinguished from the healthy by the hyperspectral modeling analysis. The results of this study show that early and nondestructive detection of HLB-infected leaves without symptoms is possible, which provides a basis for the hyperspectral diagnosis of citrus with HLB.

First Report of Rust Caused by Aecial Stage of Puccinia klugkistiana on Ligustrum japonicum in Korea

Ligustrum japonicum Thunb. (Oleraceae), called Japanese privet or waxleaf privet, is native to Japan and southern Korea. Owing to its attractive evergreen foliage, it is widely cultivated in other regions with warm temperate climates. This shrub is also naturalized in California and in the southeastern United States from Texas to Virginia (https://www.invasiveplantatlas.org/). In June 2016, hundreds of L. japonicum shrubs were found affected by a rust at a disease incidence of 50% in a public garden in Daegu (35°53′25″N; 128°35′01″E), Korea. Similar symptoms with typical rust pustules on this plant species were also found in Jinju (35°10′46″N; 128°05′48″E), Korea. Examination of an affected plant revealed that orange-yellow rust pustules were formed on the lower leaf surface with corresponding yellowish to chlorotic lesions on the upper surface. Four representative voucher specimens have been deposited in the Korea University herbarium (KUS-F29287, F29290, F29781, and F29797), Seoul, Korea. Morphological characteristics of the aecial stage were as follows. Spermogonia were epiphyllous, aggregated, initially yellow and becoming brown, subepidermal, and flask shaped. Aecia were hypophyllous, densely clustered, on leaves and occasionally also on branches, causing distortion and hypertrophy of the host, cupulate, deeply immersed in host mesophyll, 120 to 200 µm diameter, and yellowish. Peridia were prominent, easily splitting vertically, peridial cells oblong to polygonal, 22 to 36 × 16 to 22 µm, inner wall 4 to 6 µm thick, verrucose, outer wall 6 to 10 µm thick, smooth to finely verrucose. Aeciospores were angularly globose to ellipsoid, densely and minutely verrucose, subhyaline to pale yellowish, 16 to 28 × 16 to 22 µm, walls 1 to 2 µm thick. Morphological characteristics of the collections were in good agreement with the aecial stage of Puccinia klugkistiana (Dietel) J.X. Ji & Kakish. (Hiratsuka et al. 1992; Ji et al. 2017). To confirm the identification, genomic DNA was extracted from aeciospores of two dried herbarium specimens. The internal transcribed spacer (ITS) and large subunit (LSU) regions of rRNA gene were polymerase chain reaction (PCR) amplified using specific primer pairs ITS5u/ITS4rust and universal primers LR0R/LR6 as described by Beenken et al. (2017). PCR products were sequenced and deposited in GenBank (MH644179 and MH644180 for ITS; MH644181 and MH644182 for LSU). No ITS sequence of P. klugkistiana is available in the NCBI database, because this this the first sequence data for ITS of this rust species. LSU sequences from two representative isolates had 100% homology with that of Aecidium klugkistianum (HQ699078) from China. The aecial stage of P. klugkistiana has been reported on eight species/varieties of Ligustrum from East Asia including China, Japan, and Korea (Farr and Rossman 2018; Hiratsuka et al. 1992). In Korea, L. ibota and L. obtusifolium have been recorded as host plants of the aecial stage of P. klugkistiana (Hiratsuka 1942). To our knowledge, this is the first report of the aecial stage of P. klugkistiana on L. japonicum in Korea. Rust infection caused necrotic lesions, greatly detracting from the beauty of the glossy leaves.

The calibration of the sprayers and the factors involved in coverage uniformity in the vineyard

The phytopathological condition of the vineyard and the reduction in the use of crop protection products are closely linked to the efficiency of the use of sprayers. The objective of the work was to identify the best operative conditions to improve the canopy coverage of the spraying. From 2012 to 2017 173 field trials were carried out in 40 farms, on 24 varieties, testing 72 different sprayers in North Eastern Italy. Water-sensitive papers of 2.5 × 2.5 cm were positioned in eight points in the vine canopy according to a standardized method, and they were examined after spraying for spray deposition. In general, results showed that coverage of the lower leaf surface was very poor. On the contrary, the upper section of leaves in the outer canopy layers have received excessive spraying, over 70% coverage in 25% of cases. The coverage uniformity was improved by using driving speeds lower than 6 km / h and using upward air flow direction.

A new genus and two new species of eriophyoid mites (Acari: Eriophyidae) from Malaysia

A new genus and two new species of the family Eriophyidae (Acari: Eriophyoidea) from Mountain Trusmadi, Malaysia are described and illustrated. They are Trusmadius acalypher gen. nov. and sp. nov. on Acalypha sp. (Euphorbiaceae) and Paraphytoptus lithocarpis sp. nov. on Lithocarpus uvariifolius (Hance) Rehder (Fagaceae). Both new species are vagrant on lower leaf surface. No damage to the host was observed.

New findings on infestation and phenology of Dasineura oleae Angelini (Diptera, Cecidomyiidae): an emerging pest on olive trees in the Palestinian Territories

Dasineura oleae is a gall midge on leaves and branches of olive trees. Due to the scarcity of information regarding to the infestation and phenology of D. oleae on olive trees, the objectives of this research were: (1) to study the pest status of D. oleae and its damage on olive trees, (2) to describe the life stages: egg, larva, pupa and adult, (3) to determine the life cycle duration and number of generations per year and (4) to describe the egg laying, larval development, pupation and adult emergence. Results indicated that there was an outbreak of D. oleae in the Palestinian Territories where the average rate of infestation on olive trees was 51.46% and the damage caused by the insect on leaves, branches and inflorescence of infested trees reached at an average infestation rate of 35.88, 22.70 and 26.54%, respectively. Eggs of D. oleae were laid on the lower leaf surface, and the hatched larvae penetrated the tissues underneath and induced galls in which they live and develop until the emergence of adults. D. oleae developed one generation per year in the hilly regions of Palestinian Territories and two generations in the coastal regions of these territories. A full description of the life stages has been provided for the insect. In conclusion, this study provides with new information regarding to the pest status of D. oleae, infestation and development of the insect on the different organs of olive trees. These findings are necessary for the insect management and its control.

Identification of a new turncurtovirus in the leafhopper Circulifer haematoceps and the host plant species Sesamum indicum.

Turncurtoviruses (family: Geminiviridae; genus: Turncurtovirus) appear to have a high degree of genetic variation in Iran. Leafhoppers of the species Circulifer haematoceps (Mulsant and Rey, 1855) (family: Cicadellidae) were collected in 2014 from three geographical regions in south-eastern Iran (Orzoeyeh, Jiroft and Sirjan; Kerman province) and screened for the presence of turncurtoviruses using a combination of PCR and rolling circle amplification (RCA) methods. Eleven genomes of turncurtovirus were recovered and sequenced. Leafhoppers were sampled off sesame (S. indicum L.) and turnip (Brassica rapa sub sp. rapa). Thus, we identified three symptomatic sesame plants (yellowing, boat-shaped leaf curling, vein swelling on the lower leaf surfaces) from sesame farms in Jiroft. In these samples, we identified the same turncurtovirus as in the leafhoppers and have named it sesame curly top virus (SeCTV). Collectively, these SeCTV share > 98% genome-wide pairwise identity and ~ 87.3% to a recently identified turncurtovirus (sesame yellow mosaic virus; SeYMV) from sesame in Pakistan (GenBank accession MF344550). The SeCTV and SeYMV sequences share < 70% genome-wide pairwise identity with isolates of Turnip curly top virus and Turnip leaf roll virus, the two species in the genus Turncurtovirus. Based on the pairwise identities and phylogenetic analysis, SeCTV (n = 12) and SeYMV (n = 1) represent two strains of a new species in the genus Turncurtovirus.

Intumescence Injury in the Leaves of Russet Burbank Potato Plants is Mitigated by Calcium Nutrition

Many plants including potato, tobacco, tomato, and geraniums often develop intumescence (oedema) injury, which is observed exclusively on plants grown in controlled environments. Early studies have suggested a link between light quality and intumescence by showing UV and/or far-red light mitigation of injury. Here, we report that intumescence can be mitigated by calcium nutrition. Commercial cultivars of Solanum tuberosum L. cvs ‘Russet Burbank’ and ‘Atlantic’ were grown from in vitro shoot cultures in 20.4 L pots within a climate-controlled greenhouse. Plants were irrigated daily to excess with Peter’s Professional Peat Lite Special 20–10-20 fertilizer (0.52 g·L−1 tap water) supplemented with either 1 mM or 10 mM CaCl2·2H2O. We evaluated 13 replications from both potato cultivars and Ca2+ treatments. Intumescences were observed at about 32 days after calcium treatments began, exclusively on the upper and lower leaf surfaces of Russet Burbank. Upper canopy leaves of Russet Burbank showed approximately 65 and 5% intumescence injury for the 1 mM and 10 mM Ca2+ treatments, respectively. Average leaf calcium concentration was nearly double in the plants supplemented with 10 mM compared with 1 mM Ca2+. Tuber yield and foliage weight were higher in the plants supplemented with 10 mM Ca2+ as compared with 1 mM Ca2+ and suggests that intumescence injury reduced growth and partitioning. These data provide evidence that supplemental calcium can mitigate intumescence injury on susceptible cultivars of potato in controlled environments.

&lt;span style="font-family: Times New Roman;"&gt;Eriophyoid mites associated with the blackberry in Brazil—a new species in the genus Diptacus Keifer 1951 (Diptilomiopidae) and first report and supplementary description of Acalitus orthomerus (Keifer, 1951) (Eriophyidae)&lt;/span&gt;

A new vagrant species of Diptilomiopidae mite, in the Diptacus Keifer, 1951 genus, namely Diptacus rubuscolum sp. nov., living on the lower leaf surface of blackberry-Rubus sp. (Rosaceae) in South Brazil, is described and illustrated. In addition, Acalitus orthomerus Keifer, 1951, for the first time reported in Brazil and even in South America; a supplementary description of this species is presented based on females, males and immature specimens associated to the drupelets. Main morphological differences distinguishing the new Diptacus species and A. orthomerus species from those belonging to the same genera or morphologically similar also associated with Rubus are presented.

PM 7/21 (2) Ralstonia solanacearum, R. pseudosolanacearum and R. syzygii (Ralstonia solanacearum species complex)

Specific scopeThis Standard describes a diagnostic protocol for Ralstonia solanacearum, Ralstonia pseudosolanacearum and Ralstonia syzygii, i.e. phylotype/sequevar strain in the Ralstonia solanacearum Species Complex (RSSC).It should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols.Specific approval and amendmentApproved in 2003‐09. First revised in 2018‐02.

Biology and morphometry of rice leaf folder, Cnaphalocrocis medinalis (Guen.) under allahabad conditions

Eggs of rice leaf folder were laid in singly and clusters of 2 to 4 and maximum (48.2%) were laid on lower surface of leaf. Full grown larvae was measured 15.55 mm in length and 1.23 mm in breadth. Male pupae was longer than female pupae. The adult moths male and female measures about 8.65 mm and 7.31 mm in length and width is 2.01 mm and 1.78 mm, respectively. The larval survival was 56.6/with 89.5% moth emergence. The pre-oviposition, oviposition and post oviposition were 1.8, 4.4 and 2.5 days, respectively average fecundity of 100.6/female. The adult moth had slender body golden yellow with black wing margins in the apical region. Males are brighter than females, wing span measured about 15 to 16 mm and 15 to 17 mm, respectively.

Enlarging the monotypic Monocarpieae (Annonaceae, Malmeoideae): recognition of a second genus from Vietnam informed by morphology and molecular phylogenetics

Chaowasku, T., A. Damthongdee, H. Jongsook, D.T. Ngo, H.T. Le, D.M. Tran & S. Suddee (2018). Enlarging the monotypic Monocarpieae (Annonaceae, Malmeoideae): recognition of a second genus from Vietnam informed by morphology and molecular phylogenetics. Candollea 73: 261–275. In English, English abstract. DOI: http://dx.doi.org/10.15553/c2018v732a11Recent botanical expeditions in central Vietnam yielded an unknown species of Annonaceae that could not be confidently identified to subfamily, tribe, and genus. Preliminary BLAST® searches based on plastid data have suggested that this taxon is genetically closely-related to the following tribes of subfamily Malmeoideae: Malmeeae, Fenerivieae, Maasieae, Phoenicantheae, Dendrokingstonieae, Monocarpieae, and Miliuseae. Using representatives of Piptostigmateae, another tribe of Malmeoideae, as outgroups and including representatives of all other tribes of Malmeoideae, molecular phylogenetic analyses of seven combined plastid markers (rbcL, matK, ndhF, ycf1 exons; trnL intron; trnL-trnF, psbA-trnH intergenic spacers) inferred the enigmatic Vietnamese taxon as belonging to the monotypic tribe Monocarpieae. Detailed morphological comparisons between this taxon and its sister group, Monocarpia Miq., warranted the recognition of a second genus of Monocarpieae to accommodate our unknown taxon: Leoheo Chaowasku with a single species, Leoheo domatiophorus Chaowasku, D.T. Ngo & H.T. Le. The morphology of the new genus agrees well with the diagnostic traits of Monocarpieae, e.g., a percurrent tertiary venation of the leaves, a highly reduced number of carpels per flower, enlarged and lobed stigmas, multiple ovules/seeds per ovary/monocarp, considerably large monocarps with a hardened pericarp when dry, and spiniform ruminations of the endosperm. However, the new genus does not exhibit two characteristic features of Monocarpia: terminal inflorescences and generally distinct intramarginal leaf veins. In addition, the new genus possesses three autapomorphic characters: hairy domatia on the lower leaf surface, longitudinal ridges on the monocarp surface, and subsessile monocarps with a stout stipe. The tribe Monocarpieae is consequently enlarged to include the genus Leoheo. The enlarged Monocarpieae, along with the recently established monotypic tribe Phoenicantheae and two other related tribes, Dendrokingstonieae and Miliuseae, are discussed.Received: November 4, 2017. Accepted: August 30, 2018. First published online: November 23, 2018.

Effects of Low Temperature on Spider Mite Control by Intermittent Ultraviolet-B Irradiation for Practical Use in Greenhouse Strawberries.

The application of ultraviolet-B (UVB) radiation to control spider mites is challenging as a key technology for integrated pest management (IPM) in greenhouse strawberries in Japan. To address this, concurrent use of phytoseiid mites and reduced UVB irradiance is desirable to ensure control effects in areas shaded from UVB radiation and to minimize the sunscald in winter, respectively. We designed experiments reproducing the UVB dose on the lower leaf surfaces in strawberry and evaluated the effects of intermittent UVB irradiation at midnight for practical application in the greenhouse and low temperature on the survival of the spider mite Tetranychus urticae Koch (Acari: Tetranychidae) and damage to the phytoseiid mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). The midnight intermittent UVB irradiation effectively suppressed egg hatching and development of larvae of T. urticae, and the control effect was reinforced at 20°C (no eggs hatched at 0.13 kJ m-2 d-1) rather than, at 25°C (70.8% eggs hatched). In contrast, the hatchability of N. californicus eggs was unaffected by intermittent UVB irradiation at 0.27 kJ m-2 d-1 at 25°C and 20°C. However, residual effects of UVB irradiation to N. californicus eggs on survival of hatched larvae were seen, so that reducing the UVB dose is also advantageous for this phytoseiid mite. N. californicus showed a photoreactivation capacity, whereas their UVB tolerance was improved by prey species, suggesting the possibility of the improvement of phytoseiid mites by diet. The reduction of UVB dose and concurrent use of phytoseiid mites increase reliability of the UVB method in IPM strategies in strawberry greenhouse.

First Report of White Blister Rust Disease Caused by Albugo occidentalis on Spinach in Turkey

Spinach (Spinacia oleracea L.) is an increasingly important vegetable crop in Turkey as is the case for many parts of the world. In March 2017, detailed field surveys were conducted to investigate the occurrence of leaf diseases in major spinach fields in Hatay Province of Turkey. White blister rust disease was sporadically present in many production fields. The disease incidence on affected crops ranged from 21 to 45% across all the areas surveyed. Initial symptoms were small chlorotic spots on the upper leaf surface. As the disease developed, white pustules (sori) or blisters were frequently produced as irregularly oval, elongated concentric rings, 3 to 4 mm in diameter, mostly on the lower leaf surface but also often on the upper surface. In the advanced stages of the disease, the white pustules often coalesced, and lesions appeared grainy due to the production of numerous oospores, rendering infected leaves unmarketable. A representative specimen (SAL2) was deposited in the Korea University Herbarium (KUS-F30037). Microscopic examination revealed that sporangia were born in basipetal chains, globose to oval, with a smooth wall surface and measured 12.5 to 15.0 × 17.5 to 20.0 μm (n = 100). The small stalked spherical haustoria, which were produced within mesophyll cells, were connected to the intercellular coenocytic hyphae, and measured 5.0 μm in diameter (n = 50). Dark-colored oospores were produced in subepidermal tissue, finely reticulated, 45 to 60 µm in diameter, with a wall thickness of 5 μm (n = 50). The morphological characteristics closely resembled those reported for Albugo occidentalis by Choi and Priest (1995). To confirm the morphological identification, both the internal transcribed spacer (ITS) rDNA and the cytochrome oxidase II (cox2) mtDNA were amplified with ITS1-O and LR0 for ITS and cox2-F and cox2-RC4 and directly sequenced (Choi et al. 2015). The resulting sequences were deposited in GenBank (accession nos. MF991148 for ITS, MF991149 for cox2). A BLASTn search revealed that the Turkish isolate is identical to the ITS and the cox2 sequences (KC676794, KC676795) of A. occidentalis in GenBank. A pathogenicity test was conducted by spraying a sporangial suspension (10⁵ sporangia/ml) onto 10 healthy leaves of 3-week-old spinach plants (cv. Matador). Inoculated plants were incubated in a dew chamber for 72 h at 18°C and then maintained in a greenhouse at 20°C with a 10-h photoperiod. Ten control plants were sprayed with distilled water and maintained under the same conditions as the inoculated plants. After 10 to 12 days, white rust pustules similar to the original symptoms observed in the field developed on inoculated plants, whereas the control plants remained symptomless. The pathogen present on the inoculated plants was morphologically identical to the original one observed on the diseased plants, fulfilling Koch’s postulates. Based on morphological characteristics, molecular sequencing data, and pathogenicity test, it was concluded that the pathogen on spinach in Turkey is A. occidentalis. The causal agent has been reported as an economically important pathogen of spinach in the United States, Mexico, Greece (Farr and Rossman 2017), and Iran (Ebrahimi and Afzali 2000). To our knowledge, this is the first report of A. occidentalis in Turkey. Although prevalence and host range of the causal disease agent is limited, major spinach production areas may be vulnerable to the introduction of this disease due to an increasing demand for this crop.

Leaf anatomy of a late Palaeozoic cycad

Today, cycads are a small group of gymnospermous plants with a limited distribution in the (sub)tropics, but they were major constituents of Mesozoic floras. Fossil leaves sporadically found in latest Carboniferous and Permian floras have putatively been ascribed to cycads. However, their true affinity remains unclear due to the lack of anatomical evidence. Virtually all modern cycads have pinnate leaves, but this type of leaf morphology is by no means unique for cycads. Pinnate leaves of Plagiozamites oblongifolius Halle 1927 with well-preserved cuticles showing the epidermal anatomy are here described from the upper Permian Xuanwei Formation of Yunnan Province, Southwest China. The cuticles show a clear differentiation into costal and intercostal zones; stomata are confined to the intercostal zones on both the upper and lower leaf surfaces. The external morphology and the epidermal anatomy of these fossil leaves are closely comparable with those of extant cycads, particularly members of the family Zamiaceae.

Ecological Studies on Cotton Mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Sternorrhyncha: ‎ Coccoidea: Pseudococcidae) on Eggplant at ‎ Sharkia Governorate, Egypt

Field experiments were conducted on cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Sternorrhyncha: Coccoidea: Pseudococcidae) which infested eggplant at Hihhya distract, Sharkia Governorate during two successive seasons 2015 and 2016. The population density, activity periods, the effects of some weather factors, number of insect generations and preferable leaf surface of of P. solenopsis were considered. The obtained results revealed that the total numbers of a live stages had four peaks of activity during the first season. They were in third week of June, third week of July, fourth week of August and second week of September. While, during the second season, three peaks of activity were noticed in the last week of June, first week of August and second week of September. The total effects of some weather factors such as maximum and minimum air temperature (˚C) and relative humidity percentage (R.H.%) showed positive significant relationship with the cotton mealybug population. P. solenopsis had three generations during the first and second seasons the first generation was taken seven weeks. While, the second and third generations took sex weeks. The first generation was during the period extended from the third week of May till the end of June, the second one took place from the first week of July till the second week of August and the third one was during the period extended from the third week of August till the third week of September. The insect pest preferred the lower leaf surface than the upper one during the first and second seasons.

Outbreak of powdery mildew caused by Sawadaea negundinis on boxelder in Iran

SummaryBoxelder (Acer negundo) is planted as ornamental and shade tree in many countries including Iran. During July 2016, boxelder trees in parks and streets of different localities in East Azarbaijan province, Iran were found to be heavily infected with powdery mildew. Whitish powdery fungal mass developed mainly on the lower leaf surface. The infected young leaves became bubbled, curled and crinkled, giving affected plants an unpleasant appearance. During September, scattered, dark brown, spherical chasmothecia were produced on the lower leaf surface. The causal agent was identified as Sawadaea negundinis based on a combination of morphological characteristics of sexual and asexual morphs and sequence data of the rDNA internal transcribed spacer region (ITS1‐5.8S‐ITS2). This study provides the first report on the occurrence of S. negundinis on boxelder in Iran.

Antioxidant Protection by Astaxanthin in the Citrus Red Mite (Acari: Tetranychidae).

Solar ultraviolet-B (UVB) radiation and radiant heat have lethal effects on plant-dwelling mites, including spider mites, and their natural enemies, such as phytoseiid mites, leading them to reside on lower leaf surfaces. Panonychus spider mites are outcompeted by Tetranychus spider mites and thus exploit upper leaf surfaces, where they are exposed to both UVB radiation and radiant heat. Panonychus spider mites are thought to produce astaxanthin constitutionally. In this study, we compared carotenoid components, antioxidant capacity, lipid peroxidation, survival, and egg production in wild-type (WTS) and albino-type strains (ATS) of Panonychus citri (McGregor). Four carotenoids (neoxanthin, violaxanthin, lutein, and carotene) and their isomers and esters were identified in both strains, but astaxanthin and its esters were present only in WTS. The singlet oxygen scavenging capacity of lipid-soluble ingredients was greater in WTS than in ATS, whereas the oxygen radical absorbance capacities of hydrophilic ingredients were equivalent between them. Lipid peroxide accumulation was clearly higher in ATS than in WTS under both UVB irradiation (25 °C) and high temperature (35 °C) conditions. The findings are consistent with an antioxidant protective function of astaxanthin in this mite. Survival periods at 38 °C were longer in WTS than in ATS, although no difference was shown at 35 °C or under UVB irradiation. Therefore, astaxanthin accumulation was shown to be a major mechanism for survival under radiant heat, although other mechanisms, such as photoreactivation, might play a major role in survival under UVB radiation.

Epidemiology of Basil Downy Mildew.

Basil downy mildew (BDM) caused by the oomycete Peronospora belbahrii is a destructive disease of sweet basil (Ocimum basilicum) worldwide. It originated in Uganda in the 1930s and recently spread to Europe, the Middle East, Americas, and the Far East. Seed transmission may be responsible for its quick global spread. The pathogen attacks leaf blades, producing chlorotic lesions with ample dark asexual spores on the lower leaf surface. Oospores may form in the mesophyll of infected leaves. The asexual spores germinate on a wet leaf surface within 2 h and penetrate into the epidermis within 4 h. Spore germination and infection occur at a wide range of temperatures from 5 to 28.5°C. Infection intensity depends on the length of dew period, leaf temperature, and inoculum dose. The duration of latent period (from infection to sporulation) extends from 5 to 10 days, depending on temperature and light regime. The shortest is 5 days at 25°C under continuous light. Sporulation requires high humidity but not free leaf wetness. Sporulation occurs at 10 to 26°C. At the optimum temperature of 18°C, the process of sporulation requires 7.5 h at relative humidity ≥ 85%, with 3 h for sporophores emergence from stomata and 4.5 h for spore formation. Sporophores can emerge under light or darkness, but spore formation occurs in the dark only. Limited data are available on spore dispersal. Spores dispersed from sporulating plants contaminate healthy plants within 2 h of exposure. Settled spores may survive on leaf surface of healthy plants for prolonged periods, depending on temperature. Seed transmission of the disease occurs in Europe, but not in Israel or the United States. P. belbahrii in Israel also attacks species belonging to Rosemarinus, Nepeta, Agastache, Micromeria, and Salvia but not Plectranthus (coleus). A Peronospora species that infects coleus does not infect sweet basil. Control of BDM includes chemical, physical, and genetic means. The fungicide mefenoxam was highly effective in controlling the disease but resistant populations were quickly selected for in Israel and Europe rendering it ineffective. A new compound oxathiapiprolin (OSBP inhibitor) is highly effective. Nocturnal illumination of basil crops controls the disease by preventing sporulation. Daytime solar heating suppressed the disease effectively by reducing spore and mycelium viability. The most effective physical means is fanning. Nocturnal fanning prevents or limits dew deposition on leaf surfaces, and as a result, infection and sporulation diminish and epidemics are prevented. Genetic resistance occurs in wild basil and its transfer to sweet basil is under way.