Weed Suppression of Living Mulch in Sugar Beets

Weed suppression in sugar beets (Beta vulgaris.) is commonly achieved with two to three post-emergent herbicide applications across the entire field. Field studies were performed, in order to investigate the weed suppressing ability of Medicago lupulina, Trifolium subterraneum and a mixture of Lolium perenne and Festuca pratensis as living mulches in sugar beet at four locations in South Germany during 2014 and 2015. Living mulches were sown 2 and 30 days after sowing (DAS) of sugar beet. Weed densities ranged from 0 to 143 plants m^?2 with Chenopodium album, Polygonum convolvulus and Polygonum aviculare being the most abundant weed species. It has been found that living mulches could reduce herbicide input up to 65?%. Weed suppression of living mulch was highest with Trifolium subterraneum (71?%). The early sown living mulches (2 DAS) revealed a 28 g m^?2 higher biomass compared to late sowing (30 DAS). However, no any linear correlation was found between living mulch biomass and weed suppression. White sugar yield (WSY) was highest in the herbicide treatments (12.6 t ha^?1). Trifolium subterraneum yielded the highest WSY of the living mulches with 11.1 t ha^?1 across all locations. Our work reveals that living mulch can play a major role in integrated plant protection by reducing herbicides in sugar beet production.     

Inhibitory effect of <Emphasis Type="Italic">Lycium europaeum</Emphasis> extracts on phytopathogenic soil-borne fungi and the reduction of late wilt in maize

The ability to control soil-borne pathogens in agriculture is highly conditioned by the restricted use of synthetic pesticides. Allelopathy, the antimicrobial activity of plant extracts, is a promising option against crop pathogens. Extracts from Lycium spp. such as L. barbarum, L. chinense and L. intricatum possess biological and therapeutic properties. Individual methanolic extracts from leaves and stems of the Mediterranean medicinal species L. europaeum collected in two locations of Tunisia were each evaluated in vitro against Verticillium dahliae (Vd), Sclerotinia sclerotiorum (Ss) and Harpophora maydis (Hm). The mycelial growth of the three fungi was significantly reduced by all the extracts at doses of 10 and 30 μl mL^?1 (equivalent to 1 and 3 mg plant tissue mL^?1). The sporulation of Hm was almost completely inhibited in all the amendments, but that of Vd was stimulated by one of the leaf extracts when 1 and 3 mg dried plant tissue mL^?1 were used. Sclerotia of Ss were formed in a smaller number, their total weight increasing at extract doses equivalent to 1 mg plant tissue mL^?1 and higher. In greenhouse, the pathogenicity of Hm was confirmed as early as 6 weeks after inoculation, since it caused significant decreases of weights in both roots and aboveground parts of maize. The detrimental effect of Hm on maize root weight in greenhouse was significantly counteracted by one of the leaf extracts added by watering. In total, 11 phenolic compounds were separated in the four extracts. The hydroxycinnamic acid family, including chlorogenic acid as a major compound, represented more than 50% of the total content in all the samples. Rutin was the most abundant flavonoid. The results of this work show the detrimental effect of L. europaeum extracts against the soil-borne pathogens Hm, Ss and Vd, and highlight their potential in crop protection if adequately developed into final products and used in combination with other tools.     

Fungicidal activity of Thai medicinal plant extracts against <Emphasis Type="Italic">Alternaria brassicicola</Emphasis> causing black spot of Chinese kale

Crude ethanol extracts and six organic solvent fractions of 10 Thai medicinal plants were evaluated for their antifungal activity against Alternaria brassicicola in laboratory and under greenhouse conditions. The results showed that the ethanol extracts of Coscinium fenestratum, Piper betle, Syzygium aromaticus and Zingiber cassumunar displayed complete mycelial growth inhibition of A. brassicicola at a concentration of 0.1%. Meanwhile, the crude ethanol extract and methanol fraction obtained from the stems of C. fenestratum revealed the greatest inhibition against A. brassicicola at 10%, forming inhibition zones 2.55–2.58 cm in diameter. In the greenhouse experiments, crude ethanol extracts of C. fenestratum and P. betle at 1% significantly (P?<?0.05) reduced the disease incidence at up to 67%, indicating promising preventive and curative activities against A. brassicicola. This activity is similar to that of iprodione, a widely used commercial fungicide. Interestingly, Illicium verum extract showed a greater curative effect (58% disease reduction) than protective effect (47% disease reduction). Because the C. fenestratum extract showed the highest activity against the black spot pathogen both in vitro and under greenhouse conditions, its methanol fraction was further analyzed by spectroscopic techniques. We found that berberine is a key active substance inhibiting mycelial growth of A. brassicicola. The results of this study showed the potential of Thai medicinal plants as alternatives to the use of synthetic fungicides for controlling black spot in Chinese kale caused by A. brassicicola.     

Search for reservoirs of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter solanacearum’ and mollicutes in weeds associated with carrot and celery crops

Currently, the main arthropod vectored pathogens associated with carrot and celery crop diseases are ˋCandidatus Liberibacter solanacearum´, Spiroplasma citri and different phytoplasma species. Mitigation strategies require elucidating whether these pathogens survive in the weeds of these Apiaceae crops, which can act as reservoirs. Weed surveys were conducted in a vegetative cycle (April to October 2012) in the spontaneous vegetation that surrounded crops affected by ˋCa. L. solanacearum´, S. citri and/or phytoplasmas. Sixty-three species of 53 genera that belong to 23 botanical families were collected in the main carrot and celery Spanish production area. Species were identified, estimating coverage and abundance, and conserved in herbarium. Samples were analysed by nested-PCR with universal primers for phytoplasmas detection, and were sequenced for identification purposes; by conventional PCR for S. citri and real-time PCR for ˋCa. L. solanacearum´. The only detected pathogens were ˋCa. Phytoplasma trifolii´ (clover proliferation group 16Sr VI-A) in Amaranthus blitoides and Setaria adhaerens and ˋCa. P. solani´ (stolbur group 16Sr XII-A) in Convolvulus arvensis. These pathogens were also sporadically detected in celery or carrot crops. Unexpectedly, neither ˋCa. L. solanacearum´ nor S. citri was detected in the weed samples, despite the relatively high prevalence of these pathogens (less than 66 % and 25 %, respectively) in the surveyed plots. This suggests that weeds do not play an epidemiological role as reservoirs in the spread of such organisms in the studied region. The use of pathogen-free seed lots and the control of vectors are crucial for preventing the introduction and spread of these economical important pathogens to new areas.     

Natural infection of <Emphasis Type="Italic">Nicandra physaloides</Emphasis> by <Emphasis Type="Italic">Tomato severe rugose virus</Emphasis> in Brazil

Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in São Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil.     

First interception of the asiatic Bamboo longhorn, <Emphasis Type="Italic">Chlorophorus annularis</Emphasis> (F., 1787) (Coleoptera,Cerambycidae) in Italy

This study provide information on the first occurrence in Italy of the Coleoptera Cerambycidae Chlorophorus annularis (Fabricius, 1787). It is a species naturally and widely distributed in Asia and in oriental tropical and subtropical areas. This cerambyx is a post-harvest pest of bamboo belonging to several genera as Bambusa, Dendrocalamus, Phyllostachys, Sinocalamus, but it can also infest cultivated plants as Citrus spp., Gossypium, Liquidambar spp., Saccharum officinarum L., Vitis spp., and Zea mays L.     

Weeds as the potential inoculum source of <Emphasis Type="Italic">Colletotrichum fructicola</Emphasis> responsible for strawberry anthracnose in Nara,Japan

Colletotrichum fructicola is a major causal agent among anthracnose pathogens of strawberry in Nara, Japan. We hypothesized that a wide range of weeds growing in and around strawberry fields are inoculum sources of the disease and investigated their potential as hosts of C. fructicola. We also examined the influence of herbicide treatment on C. fructicola sporulation on weeds. The fungus was detected on 31 of 541 (5.7%) leaves sampled from 13 weed species from 2005 to 2008. The fungus was most frequently isolated from leaves of Amaranthus blitum with an isolation frequency of 17.9%; inoculation of A. blitum with the pathogen caused brown leaf spots. Other weeds such as Digitaria ciliaris, Galinsoga ciliata, Solidago altissima, Erigeron annuus, and Sonchus oleraceus were found to harbor the fungus at lower rates (4.3–8.1%) without symptoms. C. fructicola formed acervuli on leaves of A. blitum, D. ciliaris, and S. oleraceus after plants were killed by a herbicide (glyphosate). These results demonstrated that infected weeds associated with strawberry cultivation are potential inoculum sources of C. fructicola, especially after herbicide treatment.     

No evidence of transmission of grapevine leafroll-associated viruses by phylloxera (<Emphasis Type="Italic">Daktulosphaira vitifoliae</Emphasis>)

Grapevine leafroll disease is associated with several species of phloem-limited grapevine leafroll-associated viruses (GLRaV), some of which are transmitted by mealybugs and scale insects. The grape phylloxera, Daktulosphaira vitifoliae (Fitch) Biotype A (Hemiptera: Phylloxeridae), is a common vineyard pest that feeds on the phloem of vine roots. There is concern that these insects may transmit one or more GLRaV species, particularly GLRaV-2, a species in the genus Closterovirus. A field survey was performed in vineyards with a high incidence of grapevine leafroll disease and D. vitifoliae was assessed for acquisition of GLRaV. In greenhouse experiments, the ability of D. vitifoliae to transmit GLRaV from infected root sections or vines to co-planted virus-free recipient vines was tested. There were no GLRaV-positive D. vitifoliae in the field survey, nor did D. vitifoliae transmit GLRaV-1, ?2, ?3, or -4LV in greenhouse transmission experiments. Some insects tested positive for GLRaV after feeding on infected source vines in the greenhouse, however there was no evidence of virus transmission to healthy plants. These findings, in combination with the sedentary behaviour of the soil biotype of D. vitifoliae, make it unlikely that D. vitifoliae is a vector of any GLRaV.     

Efficacy of a formulated product containing <Emphasis Type="Italic">Quillaja saponaria</Emphasis> plant extracts for the control of root-knot nematodes

The nematicidal effect of a formulated product containing extract from Quillaja saponaria was evaluated against the root-knot nematodes. The product QL Agri® 35 (QL) was tested to record the effect on second stage juveniles motility, egg hatch and also against field populations in greenhouse experiments contacted in three different locations of Greece. Convulsive movement of second stage juveniles of Meloidogyne incognita was recorded after exposure for 8 days at a series of doses, while the most paralyzed juveniles were counted at the dose of 8 mg l^?1. There was also a gradual decrease in the number of juveniles emerging from egg masses of the same nematode species when the dose of Q. saponaria was increased from 0 to 8 mg l^?1. In greenhouse experiments, the use of Q. saponaria could control root-knot nematodes and prevent nematodes increase in soil. The present study demonstrates that the use of Q. saponaria extract has the ability to control root-knot nematodes. Control given by Q. saponaria in field populations infecting cucumber was similar to that of cadusafos (Rugby®) and oxamyl (Vydate®) under the tested dosages and the specific conditions of the experiments.     

Response of some moss species to different controlled environmental conditions in order to use in Landscaping

Nowadays, integrating moss among decorative plants in urban landscape architecture can be an important alternative to horticulture. Especially using moss design for covering roofs and walls it could be an interesting element to improve the life/-airquality. Introducing moss design using hydroponic systems requires finding the best technologies for cultivating the species that can be used by landscape architecture. The study has been performed at the University of Applied Science Osnabrueck, Germany, in 2015 and it consisted in testing several species of common moss in what concerns their behavior to environmental conditions controlled in the greenhouse, with the scope of hydroponic growing. 6 species of moss: Totula ruralis Hedw., Camptothecium sericeum Hedw, Ceratodon purpureus Hedw., Grimmia pulvinata Hedw, Racomitrium aciculare Hedw. and Bryum capillare Hedw., have been transplanted from a natural habitat to the greenhouse and their behavior to different water dosing and light intensity was checked. After the observations made using the principle of rating, it was concluded that the species Grimmia pulvinata and Ceratodon purpureus adapted the best to the controlled environment and this quality makes them suitable to be used in landscape design.     

Transgenic citrus expressing the antimicrobial gene <Emphasis Type="Italic">Attacin E</Emphasis> (<Emphasis Type="Italic">attE</Emphasis>) reduces the susceptibility of ‘Duncan’ grapefruit to the citrus scab caused by <Emphasis Type="Italic">Elsinoë fawcettii</Emphasis>

Citrus scab, caused by Elsinoë fawcettii (anamorph Sphaceloma fawcettii), is a common foliar fungal disease affecting many citrus cultivars, including grapefruit. No commercial grapefruit cultivar is resistant to scab, and the disease results in severely blemished fruit which reduces its marketability. Transgenic ‘Duncan’ grapefruit trees expressing the antimicrobial attE gene were produced via Agrobacterium-mediated transformation. In in vitro leaf and greenhouse assays, several transgenic-lines had significantly lower susceptibility to E. fawcettii compared to the non-transformed control (P?P?P?attE mRNA was inversely related to the number of copies detected by Southern blot. The least susceptible line had a single inserted copy of the attE transgene whereas more susceptible lines had multiple copies. Since the attacin mode of action was thought to be specific to Gram-negative bacteria, it was unexpected to find that there was a significant activity against E. fawcettii.     

Conidial sporulation of <Emphasis Type="Italic">Stemphylium solani</Emphasis> under laboratory conditions and infectivity of the inoculum produced <Emphasis Type="Italic">in vitro</Emphasis>

Potato virus Y (PVY) is the type-species of the genus Potyvirus, family Potyviridae, being reported as a major tomato (Solanum lycopersicum L.) pathogen in several regions of the world. Pepper yellow mosaic virus (PepYMV) was originally described as a resistance-breaking Potato virus Y (PVY) isolate on Capsicum annuum L. cultivars, and afterwards it was also reported infecting tomatoes in Brazil. In the present work, a search for sources of resistance to both PepYMV and PVY was conducted in a collection of 119 accessions belonging to seven Solanum (section Lycopersicon) species. This germplasm was initially evaluated to PepYMV reaction by mechanical inoculation followed by symptom observations and ELISA. Potential PepYMV resistance sources were identified for the first time in S. habrochaites, S. peruvianum, S. corneliomuelleri, S. chilense, S. pimpinellifolium, and one accession derived from an interspecific cross (S. lycopersicum x S. peruvianum). A sub-group of 24 accessions with negative serology for PepYMV was also challenged with a PVY isolate, followed by serological and molecular detection with universal primers. Solanum habrochaites ‘L.03683’ and ‘L.03684’ were the only accessions found with stable resistance to both viruses. These results confirm S. habrochaites as the most important source of multiple resistance factor(s) to distinct Potyvirus species.     

White rust and downy mildew on new hosts in Turkey

Albugo convolvulacearum (Otth.) Kuntze on Convolvulus pentapetaloides L. and C. siculus L. subsp. siculus, and Peronospora trigonellae Gäum. on Trigonella cariensis Boiss., were collected for the first time in Turkey. The fungi species, including their macro- and microscopic features and distributions, are described.     

Artemia sp. Cysten als Aufzuchtfutter für Macrolophus pygmaeus: eine Evaluation unter Praxisbedingungen

Macrolophus pygmaeus is an omnivore insect with beneficial characteristics because of its good feeding performance and broad host range. However, disadvantages for its use are the high purchase and rearing costs. Labortary experimants showed that the breeding of this predatory bug is also possible with the eggs of Artemia sp. The objective of the present study therefore was to test Artemia sp. cysts as a food alternative for Macrolophus pygmaeus under practical conditions. For this purpose, a population of this bug was grown in glasshouse departments of the Research Center for Horticulture in Straelen, Germany. Three glasshouse compartments served as control treatments and were fed with E. kuehniella; the other three compartments were fed with cysts of Artemia sp. The population of M. pygmaeus, that has been raised with Artemia sp., turned out to be significantly smaller than the control. In this greenhouse trial, Artemia sp. cysts turned out to be an unsuitable alternative, because no stable and powerful population of M. pygmaeus could be established. However, this trial has been conducted under real practice conditions in the greenhouse, where because of the complexity of the system further research is needed to identify the specific reasons or factors of influence being responsible for the different outcome of experiments conducted under lab and practice conditions.     

Species of Botryosphaeriaceae associated on mango in Brazil

The aim of the present study was to assess diversity in the Botryosphaeriaceae on trees and fruit of mango (Mangifera indica L.) in a semi-arid region in northeastern Brazil in which most exported fruit in the country are produced. Using morphological characteristics and DNA sequence data (ITS-1, ITS-2 and 5.8S rDNA) we confirmed the presence of Lasiodiplodia theobromae in the region, and for the first time report Fusicoccum aesculi and Neofusicoccum parvum. L. theobromae was prevalent in the Assú Valley and F. aesculi and N. parvum were in the São Francisco Valley. In fruit inoculations, L. theobromae and N. parvum were more virulent than F. aesculi.     

Carabidae as potential biological agents for controlling infestations of the cabbage root fly

Laboratory tests with carabid ground beetles found in Wellesbourne fields indicated that intermediate-sized beetles such asBembidion tetracolum, Amara familiar is andAgonwn dorsale were more effective predators of cabbage root fly (Erioischia brassicae) eggs than small beetles, e.g.Bembidion lampros andTrechus quadristriatus, or large beetles, e.g.Harpalus rufipes andPterostichus melanarius. Further tests indicated thatA. dorsale would be an ideal predator, as it can survive up to one month without food, is not killed byP. melanarius, aggregates naturally, and eats large numbers of cabbage root fly eggs/larva.A. dorsale is also relatively easy to retain near the stems of plants by simple barriers and is not cannibalistic. Unfortunately, sufficientA. dorsale were not available for greenhouse trials. Greenhouse trials withB. tetracolum indicated that two beetles per plant were sufficient to control the high levels of cabbage root fly infestation normally encountered in the field at Wellesbourne.     

Population dynamics of <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> on cucumber grafted onto the Cucurbita hybrid RS841 or ungrafted and yield losses under protected cultivation

The influence of the squash hybrid RS841 rootstock (Cucurbita maxima x C. moschata) on population dynamics of Meloidogyne incognita and yield of cucumber cv. Dasher II was assessed during 2013 and 2014 in a plastic greenhouse. In addition, the relationship between ecophysiological parameters (plant water status, gas exchange, and leaf reflectance) and Pi and cucumber yield were also estimated in 2013. Nematode densities were determined at the beginning (Pi) and at the end (Pf) of each crop, and the relationship between these parameters was used to estimate the maximum multiplication rate (a), the maximum population density (M) and the equilibrium density (E) per grafted and ungrafted cucumber and cropping season. Moreover, the relationship between the multiplication rate (Pf/Pi) and Pi was compared between grafted and ungrafted cucumber per cropping season. Finally, the relative yield of grafted or ungrafted cucumber was plotted against Pi to determine the tolerance limit (T) and the minimum relative yield (m) by the Seinhorst damage function model. Values of a, M and E in grafted cucumber were higher than in ungrafted one irrespective of the cropping season. These results were supported by comparing the relationship between Pf/Pi and Pi between grafted and ungrafted cucumber. The relationship between Pi and yield fitted the Seinhorst damage function. The values of T and m did not differ between grafted and ungrafted each year. Predawn water potential, net photosynthetic rate, and leaf chlorophyll index decreased with increasing Pi. In addition, relative yield was related to variation in net photosynthetic rate and the leaf chlorophyll index. Under the conditions of this study, RS841 rootstock was neither resistant nor tolerant to M. incognita.     

Resistance to root-knot nematodes on passion fruit genotypes in Brazil

With the expansion of passion fruit cultivation in Brazil, phytosanitary problems have increased, among them, the occurrence of root-knot nematodes. This research aimed to study the response of passion fruit genotypes to Meloidogyne incognita, M. javanica and M. enterolobii in addition to evaluating the life cycle of M. enterolobii in the passion fruit genotype ‘FB 200’. The genotype response was carried out in a greenhouse. Each pot’s soil was inoculated with 5000 eggs. Gall index, egg mass index and nematode reproduction factors were evaluated at 120 days after inoculation. All genotypes studied were resistant to M. incognita, M. javanica and M. enterolobii, except ‘Roxinho do Kênia’, which was susceptible to the three nematode species. The life cycle of M. enterolobii in “FB 200” passion fruit was studied in a growth chamber at 26 °C with a photoperiod of 12 h. Seven days after transplantation, each plant was inoculated with approximately 400 second-stage juveniles. Evaluations were done at 7, 14, 21, 28, 35, 42 and 49 days post inoculation. The nematode did not complete its life cycle.     

Integrative identification and molecular phylogeny of dagger and needle nematodes associated with cultivated olive in Tunisia

The occurrence and geographic distribution of longidorid nematode species inhabiting the rhizosphere of cultivated olive (cvs. Chemlali and Chétoui) in Tunisia were investigated. Morphological and morphometrical studies identified three Longidorus and six Xiphinema species, with frequencies of prevalence as following: Longidorus africanus (23.0 %), L. euonymus (4.5 %), L. glycines (13.7 %), Xiphinema conurum (13.7 %), X. italiae (36.4 %), X. meridianum (13.7 %), X. pachtaicum (18.2 %), X. robbinsi (9.1 %), and Xiphinema sp. (4.5 %). The three Longidorus species were reported for the first time in Tunisia, in addition to two species of Xiphinema (viz. X. meridianum and X. robbinsi). Molecular characterisation using D2-D3 expansion regions of 28S rRNA and ITS1-rRNA was carried out and Bayesian inference analysis was used to reconstruct phylogenetic relationships among these species and with other longidorids. Twenty-five new D2-D3 of 28S rRNA gene sequences were obtained in the present study, seven for Longidorus and 18 for Xiphinema spp., as well as 14 new ITS1 rRNA gene sequences (seven for Longidorus and seven for Xiphinema spp.).     

Relative potency of culture supernatants of <Emphasis Type="Italic">Xenorhabdus</Emphasis> and <Emphasis Type="Italic">Photorhabdus</Emphasis> spp. on growth of some fungal phytopathogens

In previous research, concentrated metabolites produced by bacteria of the genera Xenorhabdus and Photorhabdus (which are symbionts of entomopathogenic nematodes) were reported to be highly suppressive to fungal and oomycete plant pathogens. Conceivably, application of non-concentrated bacterial filtrates would be more economically feasible compared to using concentrated metabolites. We evaluated the potency of 10 % v/v cell-free supernatants of the bacteria X. bovienii, X. nematophila, X. cabanillasii, X. szentirmaii, P. temperata, P. luminescens (VS) and P. luminescens (K22) against Fusicladium carpophilum (peach scab), F. effusum (pecan scab), Monilinia fructicola (brown rot), Glomerella cingulata (anthracnose) and Armillaria tabescens (root rot). A bioactive compound derived from Photorhabdus bacteria, trans-cinnamic acid (TCA), was also compared with the bacterial filtrates. Fungal colony size based on manual measurements was compared for accuracy to measurements taken by image analysis. Supernatants of Xenorhabdus spp. exhibited stronger suppressive effects on spore germination and vegetative growth when compared with Photorhabdus spp. Overall, TCA was the most effective treatment; vegetative growth was completely inhibited by TCA (1.27 mg/ml). TCA treatments also suppressed spore germination of F. carpophylium and F. effussum by approximately 90 %. The efficacy of supernatants varied among Xenorhabdus species depending on the species tested, but X. szentirmaii filtrates tended to cause greater inhibition relative to the other bacteria supernatants. Manual measurement of colony diameter required at least two replicate estimates of the colony to avoid a type II error. Area measurements were slightly overestimated based on ruler measurements, but did not affect the outcome of the analysis. Supernatants of Xenorhabdus spp., Photorhabdus spp., or TCA, did not cause any phytotoxic effects when applied to various plant species in the greenhouse. Our results indicate the potential of using TCA or Xenorhabdus cell free supernatants as bio-fungicides. Such a product, based on bacterial culture supernatants, would be economically viable, marketable and easily applicable by the end-users in many situations.