Efficacy of Boric Acid,Monopotassium Phosphate and Sodium Metabisulfite on the Control of Apple Scab

In vitro experiments indicated that boric acid, monopotassium phosphate, sodium metabisulfite and synthetic fungicide fluopyram + tebuconazole were effective in inhibiting conidia germination and germ‐tube elongation of Venturia inaequalis. Monopotassium phosphate even at the highest concentration used in the study reduced conidia germination and germ‐tube elongation of V. inaequalis by 22.1% and 28.8%, respectively; however, the difference between two compounds at lower concentrations except 0.05% (for conidia germination) and 0.1% (for germ‐tube elongation) of boric acid was statistically significant (P ≤ 0.05). Complete inhibition was achieved by 0.01% sodium metabisulfite, 0.035% fluopyram + tebuconazole and 0.2% boric acid. Two orchard trials were conducted on the highly susceptible cv. Mutsu to apple scab to ascertain the efficacy of 0.2% boric acid, 0.5% monopotassium phosphate, 0.5% sodium metabisulfite and 0.035% fluopyram + tebuconazole for the control of apple scab. In both 2013 and 2014, except for the applications of monopotassium phosphate and sodium metabisulfite, the applications of boric acid and fluopyram + tebuconazole to trees at 10‐day intervals significantly reduced disease incidence and severity on leaves and fruit compared to the water‐treated control. In both years, the efficacy of boric acid and fluopyram + tebuconazole treatments was similar in reducing both disease incidence and severity on leaves and fruit in all monthly assessments from July to September. All treatments were neither phytotoxic to leaves and fruit nor did they adversely affect quality parameters of harvested fruit. These results show that boric acid treatment may be applied as an alternative chemical for the control of apple scab.     

Effects of Copper Toxicity on Leaves of Oregano (Origanum vulgare subsp. hirtum)

The effects of increasing concentrations of soil copper on anumber of leaf structural parameters in oregano plants werestudied to determine the effect of copper toxicity. Copper-stressedleaves were small and chlorotic and underwent a thickening oftheir lamina, due principally to an increase in the number andvolume of mesophyll cells. The number of stomata and glandularand non-glandular hairs increased significantly. Chloroplastsof mesophyll cells declined dramatically in number and volume.Grana and stroma thylakoids of chloroplasts did not undergoany noticeable alterations, but starch grains disappeared, plastoglobulibecame larger and the double membrane limiting the chloroplastbecame dilated. Leaf chlorosis was determined by total chlorophyllanalysis and measurement of the leaf Cu, Fe and Mg content.The effects of copper toxicity on oregano leaves comprised significantstructural alterations which reflect reduced metabolic activity.Copyright 2001 Annals of Botany Company Origanum vulgare subsp, hirtum, oregano, copper toxicity, leaf, structure and ultrastructure, morphometry, inorganic elements, tissue relative volumes     

Chemical Composition and Biological Activity of the Essential Oil of Origanum vulgare ssp. hirtum from Different Areas in the Southern Apennines (Italy)

The chemical composition of the essential oils of Origanum vulgare ssp. hirtum, growing wild in three different localities in the Southern Apennines, was studied by GC‐FID and GC/MS analyses. In total, 103 compounds were identified. The oils were mainly composed of phenolic compounds and all oils belonged to the chemotype carvacrol/thymol. The three essential oils were evaluated for their in vitro phytotoxic activity by determining their influence on the germination and initial radicle elongation of Sinapis arvensis L., Phalaris canariensis L., Lepidium sativum L., and Raphanus sativus L. The seed germination and radicle growth were affected in various degrees. Moreover, the antifungal activity of the three essential oils was assayed against three species causing pre‐ and postharvest fruit decay (Monilinia laxa, M. fructigena, and M. fructicola). At 1000 ppm, the three oils completely inhibited fungal growth. The hemolytic activity of the oils was assayed and showed no effect on the cell membranes of bovine erythrocytes.     

Inhibitory effect on soybean lipoxygenase and docking studies of some secondary metabolites,isolated from Origanum vulgare L. ssp. hirtum

In this study, five secondary metabolites (caffeic acid, rosmarinic acid, lithospermic acid B, 12-hydroxyjasmonic acid 12-O-β-glucoside and p-menth-3-ene-1,2-diol 1-O-β-glucopyranoside) isolated from the polar extracts of the plant Origanum vulgare L. ssp. hirtum, were tested in vitro for their ability to inhibit soybean lipoxygenase. Among the examined compounds, lithospermic acid B demonstrated the best inhibitory activity on soybean lipoxygenase with IC₅₀ = 0.1 mM. Docking studies have been undertaken as an attempt for better understanding the interactions of these compounds within the active site of soybean lipoxygenase. The predicted binding energy values correlated well with the observed biological data.     

Influence of Morphological Variability and Habitat on the Chemical Composition of Essential Oils of an Algerian Endemic Origanum Species (Origanum floribundum Munby)

The genus Origanum L. (Lamiaceae) enjoys a socioeconomic interest and constitutes one of the most popular spices. In the literature, the study of this taxon is limited mainly to the chemical composition, antimicrobial, antifungal, and antioxidant activities of the essential oils. In Algeria, few works have been done in this area, including the endemic and rare species: Origanum floribundum Munby . In this study, our contribution highlights the influence of the ecological parameters and of the variation of morphological traits on the chemical composition and the antioxidant activity of the essential oils of six populations. The major oils constituents are carvacrol, γ‐terpinene, and p‐cymene with carvacrol predominance (31.8 – 60.8%) in over five populations (MS1 – MS4 and MS6). However, the population of Ain Terraeur (MS5) of which individuals present a foliar polymorphism, distinguishes itself by p‐cymene predominance (42.6%). This would denote a new chemotype and/or variety which seem well differentiated on the dendrogram of the Ascending Hierarchical Classification (A.H.C) and its foliar morphology. The antioxidant activity of the six samples evaluated by the scavenging activity of free radicals DPPH^? and ABTS^?+ showed a potent efficiency for the sample with foliar polymorphism population (IC₅₀ = 51.6 ± 0.31 and 12.71 ± 0.37 μg/ml, respectively).     

Summer Epidemics of Apple Scab: The Relationship between Measurements and their Implications for the Development of Predictive Models and Threshold Levels under Different Disease Control Regimes

A 2‐year study on epidemic progress of apple scab was conducted at Randwijk, the Netherlands, in 1998 and 1999. The summer epidemic caused by conidia was studied instead of the well‐described spring season epidemic originating from ascospores. The aim was to investigate relationships between disease measurements, i.e. disease incidence and severity measures of apple scab, and their implications for the development of predictive models and threshold levels. The study characterized good relationships between the measurements on cultivar Jonagold using regression analyses in three disease control regimes (untreated, organic and integrated). For fruit quality prediction, the relationship between fruit incidence (I_f) and leaf incidence (I_l) in the organic control regime was given by I_f = 1.966 + 0.402 × (I_l) (R² = 0.92). As a result of low level of disease in the integrated control regime, shoot incidence (I_s), with higher values than leaf incidence, was better suited for prediction. The relationship was given by I_f = ?0.162 + 0.028 × (I_s) (R² = 0.91). For the integrated control regime, disease threshold levels were constructed for timing of the final fungicide application. If an apple grower wants to keep fruit infection under 1% incidence (harvest scab threshold), the timing of the final fungicide application (action threshold) should correspond to 4% shoot scab incidence at the beginning of August. The results are compared with similar studies and their biological interpretation is discussed.     

Congruence of Phytochemical and Morphological Profiles along an Altitudinal Gradient in Origanum vulgare ssp. vulgare from Venetian Region (NE Italy)

Plants of Origanum vulgare L. ssp. vulgare from the Veneto region (NE Italy) were selected to study the variability of the essential‐oil composition from leaves and inflorescences throughout an elevation gradient. We investigated also the morphology of non‐glandular and glandular trichomes, their distribution on the vegetative and reproductive organs, as well as the histochemistry of the secreted products, with special focus on the terpenoidic fraction. Since glandular trichomes are prerequisite for the essential‐oil synthesis, the second objective was to establish whether its production is related to glandular hair number, and density. Essential‐oil contents decline with increasing altitude, and the micromorphological observations revealed a decrease in trichome density along the same direction. Moreover, GC/MS analysis together with principal component analysis (PCA) showed that the three investigated populations were significantly different in chemical composition. Therefore, an important interpopulation variability for low‐, mid‐, and high‐altitude sites was established, suggesting the likely occurrence of different biotypes associated with altitudinal levels. Hence, the involvement of abiotic factors such as temperature and drought in the chemical polymorphism of O. vulgare associated with elevation is briefly discussed.     

BrpSPL9 (Brassica rapa ssp. pekinensis SPL9) controls the earliness of heading time in Chinese cabbage

The leafy heads of cabbage (Brassica oleracea), Chinese cabbage (Brassica rapa ssp. pekinensis), Brussels sprouts (B. oleracea ssp. gemmifera) and lettuce (Lactuca sativa) comprise extremely incurved leaves that are edible vegetable products. The heading time is important for high quality and yield of these crops. Here, we report that BrpSPL9‐2 (B. rapa ssp. pekinensis SQUAMOSA PROMOTER BINDING‐LIKE 9‐2), a target gene of microRNA brp‐miR156, controls the heading time of Chinese cabbage. Quantitative measurements of leaf shapes, sizes, colour and curvature indicated that heading is a late adult phase of vegetative growth. During the vegetative period, miR156 levels gradually decreased from the seedling stage to the heading one, whereas BrpSPL9‐2 and BrpSPL15‐1 mRNAs increased progressively and reached the highest levels at the heading stage. Overexpression of a mutated miR156‐resistant form of BrpSPL9‐2 caused the significant earliness of heading, concurrent with shortening of the seedling and rosette stages. By contrast, overexpression of miR156 delayed the folding time, concomitant with prolongation of the seedling and rosette stages. Morphological analysis reveals that the significant earliness of heading in the transgenic plants overexpressing BrpSPL9‐2 gene was produced because the juvenile phase was absent and the early adult phase shortened, whereas the significant delay of folding in the transgenic plants overexpressing Brp‐MIR156a was due to prolongation of the juvenile and early adult phases. Thus, miR156 and BrpSPL9 genes are potentially important for genetic improvement of earliness of Chinese cabbage and other crops.     

Plant defense against fall armyworm in micro‐sympatric maize (Zea mays ssp. mays) and Balsas teosinte (Zea mays ssp. parviglumis)

Maize [Zea mays L. ssp. mays (Poaceae)] was domesticated from Balsas teosinte (Zea mays ssp. parviglumis Iltis & Doebley) in present‐day Mexico. Fall armyworm, Spodoptera frugiperda JE Smith (Lepidoptera: Noctuidae), is among the most important pests of maize in Mexico and Central America. We compared the strength of plant defenses against fall armyworm between micro‐sympatric landrace maize and Balsas teosinte in the field and laboratory. The field comparison, conducted in Mexico, consisted of comparing the frequency of fall armyworm infestation between young maize and Balsas teosinte plants in dryland agricultural fields in which Balsas teosinte grew as a weed. The laboratory comparison contrasted the performance of fall armyworm larvae provided a diet of leaf tissue excised from maize or Balsas teosinte plants that were intact or had been primed by larval feeding. In the field, maize plants were more frequently infested with fall armyworm than Balsas teosinte plants: over 3 years and three fields, maize was infested at a ca. 1.8‐fold greater rate than Balsas teosinte. In the laboratory, larval growth, but not survivorship, was differently affected by feeding on maize vs. Balsas teosinte, and on primed vs. intact plants. Specifically, survivorship was ca. 98%, and did not differ between maize and Balsas teosinte, nor between primed and intact plants. Larvae grew less on intact vs. primed maize, and similarly on intact vs. primed Balsas teosinte; overall, growth was 1.2‐fold greater on maize compared to Balsas teosinte, and on primed compared to intact plants. Parallel observations showed that the differences in growth could not be attributed to the amount of leaf tissue consumed by larvae. We discuss our results in relation to differences in the strength of plant defenses between crops and their ancestors, the relevance of unmanaged Balsas teosinte introgression in the context of fall armyworm defenses in maize, and whether greater growth of larvae on primed vs. intact plants signifies herbivore offense.     

Plastid phylogenetics of Oceania yams (Dioscorea spp., Dioscoreaceae) reveals natural interspecific hybridization of the greater yam (D. alata)

Phylogenetic relationships of Oceanian staple yams (species of Dioscorea section Enantiophyllum) were investigated using plastid trnL‐F and rpl32‐trnL^(UAG) sequences and nine nuclear co‐dominant microsatellites. Analysis of herbarium specimens, used as taxonomic references, allowed the comparison with samples collected in the field. It appears that D. alata, D. transversa and D. hastifolia are closely related species. This study does not support a direct ancestry from D. nummularia to D. alata as previously hypothesized. The dichotomy in D. nummularia previously described by farmers in semi‐perennial and annual types was reflected by molecular markers, but the genetic structure of D. nummularia appears more complex. Dioscorea nummularia displayed two haplotypes, each corresponding to a different genetic group. One, including a D. nummularia voucher from New Guinea, is closer to D. tranversa, D. alata and D. hastifolia and encompasses only semi‐perennial types. The second group is composed of semi‐perennial and annual yams. However, some of these annual yams also displayed D. alata haplotypes. Nuclear markers revealed that some annual yams shared alleles with D. alata and semi‐perennial D. nummularia, suggesting a hybrid origin, which may explain their intermediate morphotypes and the difficulty met in classifying them.     

Using gravel for environmental enrichment in salmonid hatcheries: The effect of gravel size during egg incubation,endogenous and first feeding in rainbow trout

Environmental enrichment aims for a deliberate increase in structural complexity in otherwise plain rearing units, helping to reduce aberrant traits and promote welfare of fish kept in captivity. Before putting enrichment protocols into practice, however, practitioners like hatchery managers need clear guidelines on enrichment measures and on the substrates used. In the present study, we used rainbow trout as a model species for salmonid rearing and investigated the use of a single layer of three different gravel types, i.e., small (4–8 mm), medium (8–16 mm) and large (16–32 mm), for environmental enrichment during egg incubation, endogenous and first feeding of rainbow trout and compared this to a barren control. From the egg stage onwards, we determined mortality, fungal prevalence as well as growth of larvae and fingerlings. We found that gravel size significantly affected mortality and fungal prevalence with the smallest gravel size and the control showing the lowest incidents. Growth of larvae and fingerlings was not affected by gravel, both when compared between gravel types and to the barren control. When using gravel for environmental enrichment in salmonid hatcheries, a small gravel size should be used. Small gravel provides the fish with a more natural environment without compromising practical feasibility of enrichment in hatcheries, still allowing for easy visual inspection and manual control of the reared fish.     

Comparative morphology of sensilla on antenna,maxillary palp and labial palp of larvae of Eucryptorrhynchus scrobiculatus (Olivier) and E. brandti (Harold) (Coleoptera: Curculionidae)

Eucryptorrhynchus scrobiculatus (Olivier) and E. brandti (Harold) are two wood boring pests of Ailanthus altissima (Mill.) Swingle (tree of heaven) and the variety Ailanthus altissima var. Qiantouchun. These beetles attack healthy trees and bore into roots and trunks during the larval stage. We studied the typology, distribution and morphostructure of the sensilla on the antennae, maxillary palps and labial palps of E. scrobiculatus and E. brandti larvae using scanning and transmission electron microscopy. The results showed the following: (i) the antennae of the two weevil larvae had two types of sensilla, sensilla basiconica (S.b.1 and S.b.2) and sensilla twig basiconica (S.tb.1‐S.tb.3), with S.tb.4 observed only on the antennae of E. brandti larvae; (ii) the maxillary palps had three types of sensilla, S.b.2, S.tb. (S.tb.2, S.tb.3 and S.tb.5) and digitiform sensilla; (iii) the labial palps had two types of sensilla, S.b.2 and S.tb. (S.tb.2, S.tb.3 and S.tb.5); (iv) the quantity and distribution of sensilla on the antennae, maxillary palps and labial palps remained constant between E. scrobiculatus and E. brandti larvae; and (v) sensilla basiconica had distinct sidewall pores, an apical pore was observed on sensilla twig basiconica, and digitiform sensilla were oval in shape, with a distinct apical pore. Based on the microstructure of the cuticle wall and dendrite, we hypothesized that these sensilla functioned as olfactory, gustatory and hygro‐/thermo‐receptors, respectively. We discuss the relationships among types of sensilla and the types of damage caused by the larvae inside the host tree to understand olfactory and gustatory receptor mechanisms. The results of this study will provide a firm basis for future electrophysiological studies.     

Suppression of Rust and Brown Eye Spot Diseases on Coffee by Phosphites and By‐products of Coffee and Citrus Industries

The rust and brown eye spot, caused by Hemileia vastatrix and Cercospora coffeicola, respectively, are the most important fungal diseases on coffee in South America. Their management is mainly by chemical treatment, and there is no genetic resistance to brown eye spot known so far. Considering the need for developing alternative products for their control, the goal of this work was to evaluate the effects of phosphites and by‐products of coffee and citrus industries on rust and brown eye spot. Formulations of coffee and citrus industry by‐products, phosphites and their combination with fungicide were evaluated in field experiments, and their effect on fungal urediniospores and conidia was evaluated in vitro. In the field, treatments were applied individually or in combination and the in vitro assays were performed with manganese phosphite (Reforce Mn), potassium phosphite and citrus industry by‐product (Fortaleza), copper phosphite and coffee industry by‐product (Fitoforce Full), and fungicide. The severity and incidence of rust and brown eye spot on coffee leaves, yield, and leaf retention were evaluated in the field. Percentage of spore germination was evaluated in vitro for both fungi, whereas mycelial growth was evaluated for C. coffeicola only. The treatments Fortaleza, Reforce Mn and Fitoforce Full suppressed both diseases with a reduction in defoliation. In the year 2012, the plants treated with Reforce Mn and Reforce Mn + Fortaleza showed a yield increase of 72 and 88%, respectively, which was similar to the results shown by the fungicide treatment. In vitro inhibition of germination of H. vastatrix urediniospores and of C. coffeicola conidia was observed and suggests that the products exert some toxic effects to both fungi. Finally, the results observed indicate that the combined use of by‐products of plant‐processing industries and phosphites is an alternative and can be added efficiently to the management of coffee diseases.     

Screening of natural products in the laboratory and the field for control of pollen beetles

Pollen beetles, Meligethes spp. (Coleoptera: Nitidulidae), are among the most damaging pests of oilseed rape (Brassica napus L.). Increasing populations of pyrethroid‐resistant pollen beetles coupled with the prohibition of synthetic pest control products in organic farming means that other direct control methods are needed. A laboratory study was therefore conducted to evaluate the effect of natural products, combinations of natural products and additives as well as natural and synthetic insecticides on mortality of pollen beetles. In addition, field trials under both integrated and organic production were conducted to evaluate the efficacy of six natural products, nine combinations of natural products, two synthetic insecticides (integrated‐production trials only), two natural insecticides and two additives to reduce pollen beetles. The laboratory trial, using both a curative and preventive approach, showed that two of the eight natural products (lavender oil and stone meal) caused a mortality of over 98% within the first day of application. The other natural products were only partially effective compared with the untreated control. In the field trials, the natural products reduced the number of pollen beetles 1 day after application compared with the untreated control in both trial years and production systems. Promising substances were stone meal, Silico‐Sec and liquid manure. Nevertheless, the efficacy was not consistent, and no effect on oilseed rape yield was observed. In spite of this, these products have the potential to control pollen beetles under field conditions with comparable effects to synthetic insecticides. Further research should therefore focus on timing and frequency of applications as well as on the formulation of the natural products to increase the persistency of the products under field conditions.     

Classification of crucigenoid algae: phylogenetic position of the reinstated genus Lemmermannia,Tetrastrum spp. Crucigenia tetrapedia,and C. lauterbornii (Trebouxiophyceae,Chlorophyta)1

The subfamily Crucigenioideae was traditionally classified within the well‐characterized family Scenedesmaceae (Chlorophyceae). Several morpho‐logical revisions and questionable taxonomic changes hampered the correct classification of crucigenoid species resulting in a high number of synonymous genera. We used a molecular approach to determine the phylogenetic position of several Tetrastrum and Crucigenia species. The molecular results were correlated with morphological and ontogenetic characters. Phylogenetic analyses of the SSU rDNA gene resolved the position of Tetrastrum heteracanthum and T. staurogeniaeforme as a new lineage within the Oocystis clade of the Trebouxiophyceae. Crucigenia tetrapedia, T. triangulare, T. punctatum, and T. komarekii were shown to be closely related to Botryococcus (Trebouxiophyceae) and were transferred to Lemmer‐mannia. Crucigenia lauterbornii was not closely related to the other Crucigenia strains, but was recovered within the Chlorella clade of the Trebouxiophyceae.