Tuber transmission of ‘Candidatus Liberibacter solanacearum’ and its association with zebra chip on potato in New Zealand

Zebra chip, an emerging disease of potatoes, has recently been associated with ‘Candidatus Liberibacter solanacearum’ in New Zealand. The phloem-limited bacterium is known to be vectored by the tomato potato psyllid (Bactericera cockerelli). In this study, the role of tuber transmission in the spread of Ca. L. solanacearum was investigated by re-planting potato tubers infected with Ca. L. solanacearum in the absence of the psyllid. Nested PCR demonstrated that Ca. L. solanacearum could be transmitted from the mother tubers both to the foliage of growing plants and to progeny tubers, resulting in symptomatic and asymptomatic plants. Of 62 Ca. L. solanacearum-infected tubers four did not sprout symptomatic of zebra chip. A further two plants developed foliar symptoms associated with zebra chip during the growing season and died prematurely. Fifty-six of the infected tubers produced asymptomatic plants, although Ca. L. solanacearum was detected in the foliage of 39 of them indicative of transmission into asymptomatic progeny plants. At harvest, Ca. L. solanacearum was found in the daughter tubers of only five of the 39 asymptomatic plants, and only one of these plants was found to have zebra chip symptoms in the daughter tubers. Our results show that tuber transmission of Ca. L. solanacearum could play a role in the life cycle of this pathogen, providing a source for acquisition by Bactericera cockerelli and for movement of the pathogen to other regions of New Zealand via transport of seed tubers.     

Correction to: Haplotypes of ‘Candidatus Liberibacter solanacearum’ identified in Umbeliferous crops in Spain

European Journal of Plant Pathology -     

Incidence of ‘Candidatus Liberibacter europaeus’ and phytoplasmas in Cacopsylla species (Hemiptera: Psyllidae) and their host/shelter plants

Psyllids, as vectors of phloem-restricted plant pathogens, are serious agricultural pests. Fruit tree phytoplasmas are transmitted by different Cacopsylla spp., while other psyllids are known vectors of liberibacters. Recently, the bacterium ??Candidatus Liberibacter europaeus?? was found in pear trees and in Cacopsylla pyri (Linnaeus), the vector of ??Ca. Phytoplasma pyri??. This new species does not cause symptoms in plants and is probably a symbiont rather than a pathogen. Based on these findings and the assumption that ??Ca. Liberibacter europaeus?? is widespread, we studied its distribution in the genus Cacopsylla and in the respective host and shelter plants (where psyllids aestivate and overwinter), as well as its possible co-presence with ??Ca. Phytoplasma?? spp. We tested 14 Cacopsylla species and 11 plant species from northwestern Italy, Hungary and Israel, characterized by warm oceanic, temperate continental and warm Mediterranean climatic conditions, respectively. ??Ca. Liberibacter europaeus?? was common within the Cacopsylla genus, being present in nine of the 14 species screened as well as in most host plants, whereas none of the shelter plants tested positive for this bacterium. Altogether, these findings indicate the presence of ??Ca. Liberibacter europaeus?? in continental zones, whereas it does not seem to be widespread in the Mediterranean region. Furthermore, lack of specific symptoms in all infected plants confirms an endophytic relationship with this bacterium, while its abundance in insects suggests a beneficial role for the host. Co-infections with phytoplasmas, observed in insects and plants, require further study to evaluate the possible interactions between them.     

SYBR Green real-time quantitative PCR for the specific detection and quantification of ‘Candidatus Liberibacter solanacearum’ in field samples from New Zealand

Diseases of solanaceous crops caused by the phloem-limited bacterium ‘Candidatus Liberibacter solanacearum’ (Lso), vectored by the tomato potato psyllid Bactericera cockerelli, pose a major economic threat to crop production. Lso is yet to be cultured and, therefore, effective control strategies depend heavily on the early detection of the pathogen via polymerase chain reaction (PCR) assays. In this study, two new assays for the detection of Lso in New Zealand field samples were developed, and compared with previously available assays. Firstly, a single-tube semi-nested gel-based PCR assay was developed for the genus-specific detection of liberibacter species, and shown to provide increased sensitivity over standard and nested PCR. Secondly, a single-tube semi-nested SYBR Green real-time PCR (qPCR) assay was developed for the specific detection of Lso in field samples from New Zealand, with a limit of detection of five copies of the target gene per reaction. Semi-nested qPCR showed similar sensitivity compared with TaqMan qPCR with the primer-probe combination LsoF-HLBpr and was 10- to 50-fold more sensitive than the conventional PCR assays tested. Quantification of titre in Lso-affected tubers by SYBR Green qPCR revealed a positive relationship between pathogen titre and the discolouration of fried tuber slices, a symptom indicative of Lso infection. Quantification of Lso in field samples of potato and tomato also revealed many samples with titres below the limit of detection of conventional PCR. The observation of low-titre samples demonstrated the utility of SYBR Green qPCR for detection of Lso, as in addition to increased sensitivity melt-curve analysis enables confirmation of qPCR data by identifying false positive results.     

So near and yet so far: the specific case of Ralstonia Solanacearum populations from Côte d'Ivoire in Africa

The genetic and phenotypic diversity of C?te d'Ivoire Ralstonia solanacearum strains was assessed on a 168-strain collection sampled on Solanaceae both in the southern lowlands and western highlands. Phylotypes I, II, and III were prevalent, though at unexpected frequencies. Phylotype I strains (87.5%) were genetically diverse and overrepresented in all agroecological areas, including highlands (AEZ III). Phylotype II strains (10.7%) only belonged to one tropical lowland-adapted broad host range lineage (IIA-35), whereas no highland-adapted potato brown rot (IIB-1) or Moko strains were detected. African phylotype III strains were rare (1.8%). They originated from a single Burkina Faso lineage (III-23) and were only found in lowlands. Three phylotype I strains were found harboring pRSC35, a plasmid identified in phylotype III strains in Cameroon. From pathogenicity tests performed on commercial varieties and tomato/eggplant/pepper references, the virulence diversity observed was high, with five pathoprofiles described. Eggplant accessions MM152 and EG203 and tomato HW7996 displayed the largest resistance spectrum and highest level. Two highly virulent phylotype I strains were able to bypass resistance of HW7996 and the eggplant reference AG91-25. Collectively, these points lead to the conclusion that the situation in C?te d'Ivoire is specific towards other African countries, and specifically from the Cameroon reference, and that within phylotype I can exist a high virulence diversity. This calls for similar studies in neighboring West African countries, linking R. solanacearum pathogen genetic diversity to strain virulence at the regional level, for the rationalization of regional resistance deployment strategies and future resistance durability studies.     

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.     

Identification of ‘Ca. Phytoplasma asteris’, banana bunchy top virus and banana streak MY virus associated with Champa and Sabri banana cultivars in Tripura,a North Eastern state of India

European Journal of Plant Pathology - Symptoms of bunchy top, little leaf, leaf chlorosis with chlorotic streaks, leaf necrosis and stunted growth were noticed in two banana cultivars, Champa and...     

Genetic diversity of ‘<Emphasis Type="Italic">Cadidatus</Emphasis> Liberibacter solanacearum’ strains in the United States and Mexico revealed by simple sequence repeat markers

‘Candidatus Liberibacter solanacearum’ is associated with the Zebra Chip (ZC) disorder of potatoes. A panel of eight simple sequence repeat (SSR) markers was developed and used to genetically characterize ‘Ca. L. solanacearum’ strains obtained from ZC-affected potato plants in the United States and Mexico. The multilocus SSR markers in this study effectively differentiated genotypes and estimated genetic diversity of ‘Ca. L. solanacearum’ strains. Genotype assignment analyses identified two major lineages of ‘Ca. L. solanacearum’ in the North American populations while only one lineage type was identified in Mexican population. No clear genetic structure was found among haplotypes based on geographical proximity or host. The high resolution power of the SSR marker system developed in this study provides a useful tool for genotyping closely related strains and tracking sources of the pathogen. Genotype information combined with epidemiological data will advance knowledge of ZC disease and will facilitate development of effective disease management.     

Invasion of Phytophthora infestans at the landscape level: how do spatial scale and weather modulate the consequences of spatial heterogeneity in host resistance?

Strategic spatial patterning of crop species and cultivars could make agricultural landscapes less vulnerable to plant disease epidemics, but experimentation to explore effective disease-suppressive landscape designs is problematic. Here, we present a realistic, multiscale, spatiotemporal, integrodifference equation model of potato late blight epidemics to determine the relationship between spatial heterogeneity and disease spread, and determine the effectiveness of mixing resistant and susceptible cultivars at different spatial scales under the influence of weather. The model framework comprised a landscape generator, a potato late blight model that includes host and pathogen life cycles and fungicide management at the field scale, and an atmospheric dispersion model that calculates spore dispersal at the landscape scale. Landscapes consisted of one or two distinct potato-growing regions (6.4-by-6.4-km) embedded within a nonhost matrix. The characteristics of fields and growing regions and the separation distance between two growing regions were investigated for their effects on disease incidence, measured as the proportion of fields with ≥1% severity, after inoculation of a single potato grid cell with a low initial level of disease. The most effective spatial strategies for suppressing disease spread in a region were those that reduced the acreage of potato or increased the proportion of a resistant potato cultivar. Clustering potato cultivation in some parts of a region, either by planting in large fields or clustering small fields, enhanced the spread within such a cluster while it delayed spread from one cluster to another; however, the net effect of clustering was an increase in disease at the landscape scale. The planting of mixtures of a resistant and susceptible cultivar was a consistently effective option for creating potato-growing regions that suppressed disease spread. It was more effective to mix susceptible and resistant cultivars within fields than plant some fields entirely with a susceptible cultivar and other fields with a resistant cultivar, at the same ratio of susceptible to resistant potato plants at the landscape level. Separation distances of at least 16 km were needed to completely prevent epidemic spread from one potato-growing region to another. Effects of spatial placement of resistant and susceptible potato cultivars depended strongly on meteorological conditions, indicating that landscape connectivity for the spread of plant disease depends on the particular coincidence between direction of spread, location of fields, distance between the fields, and survival of the spores depending on the weather. Therefore, in the simulation of (airborne) pathogen invasions, it is important to consider the large variability of atmospheric dispersion conditions.     

Root lesion nematode,Pratylenchus penetrans,in ‘Fire King’ lilies: attack and control with aldicarb

In field trials on fumigated sandy soil planted with stock of Fire King lilies lightly infested withPratylenchus penetrans, nematode control with aldicarb did not influence growth and yield of the lilies in the first growing season, perhaps because of the low initial number of nematodes. In the second season, however, a clear relation appeared between yield and nematode control by aldicarb.In such a biennial crop, yields after aldicarb treatment at planting were almost as good as after treatment in both years, 3 kg aldicarb a.i./ha (1.6 mmol.m^–2) being optimum.Samenvatting Bij de bestrijding van wortellesieaaltjes moet niet alleen rekening worden gehouden met de in de grond aanwezige aaltjes maar ook met die in de wortels van het plantgoed. Aan de wortels van het plantgoed is de aanwezigheid van deze aaltjes niet altijd duidelijk te zien. In als goed gekwalificeerd plantmateriaal van de leliecultivar Fire King werden gemiddeld 15Pratylenchus penetrans per bol gevonden en in slecht plantgoed 9.De aaltjes in de grond kunnen effectief worden bestreden door toepassing van grondontsmetting met een aaltjesdodend middel. In een tweejarige teelt van licht besmet plantmateriaal is dit echter onvoldoende om schade te voorkomen. Dit bleek uit een proef met Fire King in vooraf ontsmette zandgrond op de proeftuin Ens. In het tweede jaar was de groei van de lelies na toepassing van aldicarb ongeveer drie maal beter dan zonder dit middel. In de wortels van de onbehandelde lelies werden ongeveer twintig keer zoveel wortellesieaaltjes gevonden als in die van de behandelde planten.Om dit tweedejaarseffect nader te analyseren en de toepassing van aldicarb beter te preciseren werd het onderzoek op de proeftuin in 1975 en 1976 voortgezet, waarbij vooral aandacht werd besteed aan de dosering en de toedieningswijze van aldicarb in de vorm van Temik 10 G.Uit het pouplatieverloop van de wortellesieaaltjes gedurende de tweejarige teelt (Fig. 3) kan worden afgeleid dat pas merkbare schade optreedt bij meer dan 300P. penetrans per 10 g wortels en meer dan 20P. penetrans per 100 ml grond in mei, wanneer de ontwikkeling van de stengelwortels plaats vindt. De gevonden besmettingen blijven in het eerste jaar in alle objekten beneden deze schadegrens en komen in het tweede jaar daarboven in de objekten waar minder dan 3 kg aldicarb a.i./ha (1,6 mmol.m^–2) is toegediend in het eerste jaar. Dit is in overeenstemming met de opbrengstresultaten (Tabel 2).Uit het verband tussen de toegediende hoeveelheid aldicarb en de relatieve opbrengst blijkt eveneens dat een hogere dosering dan 1,6 mmol.m^–2 nog slechts weinig effectiever is en mogelijk zelfs groeiremmend kan werken. Het maakt daarbij weinig verschil of de toediening plaats vindt bij het planten in de vore of kort voor de opkomst van de lelies in de rug (Tabel 1). Uit praktische overwegingen moet de voorkeur worden gegeven aan de toediening in de plantvoor.De toediening van aldicarb in beide jaren had slechts een geringe produktieverhogend effect boven toediening uitsluitend in het eerste jaar (Tabel 2). Blijkbaar is de effectiviteit van dit nematicide veel groter tegen de lichte aanvangsbesmetting met aaltjes in de wortels van het plantgoed dan wanneer het in de rug wordt toegediend aan de veel hogere, verspreide besmetting aan het begin van het tweede jaar.Wat betreft de bewortelingskwaliteit van de bollen valt het op (Tabel 3) dat ook hogere doseringen dan 1,6 mmol.m^–2 nog verbetering geven en dat toediening in beide jaren een betere bewortelingskwaliteit geeft dan wanneer alleen in het eerste jaar aldicarb wordt toegediend. Het nematicide aldicarb heeft slechts een werkingsduur van 1 à 2 maanden, zodat de aaltjes zich later in het seizoen weer sterk kunnen vermeerderen waardoor de kwaliteit van de wortels snel kan teruglopen. Om een betere bewortelingskwaliteit te bereiken wordt dan ook een veel effectievere bestrijding van de wortellesieaaltjes gevraagd dan voor het veiligstellen van de groei en de opbrengst van lelies.Aangezien de bolwortels van ondergeschikte betekenis zijn voor de groei en de opbrengst van deze lelies lijkt het niet verantwoord hogere doseringen dan 1,6 mmol.m^–2 toe te passen.     

Need for flagella for complete virulence of Pseudomonas syringae pv. tabaci: genetic analysis with flagella-defective mutants ?fliC and ?fliD in host tobacco plants

The flagellins purified from Pseudomonas syringae pv. tabaci induce a hypersensitive reaction in nonhost tomato cells. To investigate the role of flagella and flagellin in the compatible interaction, we generated two types of flagella-defective mutant. The fliC mutant lost the fliC gene that encodes flagellin protein, whereas the fliD mutant lost the fliD gene that encodes HAP2-capping protein. The two mutants had markedly reduced ability to cause disease symptoms in tobacco leaves. Furthermore, propagation of the mutants in tobacco leaves was less than that in wild-type pv. tabaci. Compared to the inoculation with wild-type pv. tabaci, inoculation with the two mutants did not markedly induce the expression of typical defense response-related genes such as PAL and hsr203J. Complementation of each fliC and fliD gene to the corresponding deficient mutant restored motility and virulence. These results indicate that flagella of P. syringae pv. tabaci are indispensable organelles for complete virulence on host tobacco plants.     

Thieves,bats and fruit flies: local ecological knowledge on the weaver ant Oecophylla longinoda in relation to three ‘invisible’ intruders in orchards in Guinea

We held interviews with 100 mango and cashew growers in Guinea, West Africa. Fewer than 20 questions dealing with the tree-inhabiting weaver ant Oecophylla longinoda were developed, based on local context and related research conducted on farmers' knowledge in other countries. More than half of the growers reported that ants protect their orchard from thieves. Apart from deterring snakes, about 46% of the growers mentioned that weaver ants reduce damage by fruit-eating bats; some reported that bats do dislike the smell of weaver ants. Whereas the relationship between ants and humans or conspicuous fruit bats is well understood, a quantitative appreciation of the effect of Oecophylla on small insect pests, such as fruit flies, is more complex. Despite the fact that 57% of the growers reported that Oecophylla had a positive effect on mango fruit quality, many classified Oecophylla as a pest due to its nuisance during harvest, and they requested the plant protection staff to help them with pesticides. Strategies to strengthen local ecological knowledge are discussed.     

The utility of the ‘Arable Weeds and Management in Europe’ database: Challenges and opportunities of combining weed survey data at a European scale

Over the last 30 years, many studies have surveyed weed vegetation on arable land. The ‘Arable Weeds and Management in Europe’ (AWME) database is a collection of 36 of these surveys and the associated management data. Here, we review the challenges associated with combining disparate datasets and explore some of the opportunities for future research that present themselves thanks to the AWME database. We present three case studies repeating previously published national scale analyses with data from a larger spatial extent. The case studies, originally done in France, Germany and the UK, explore various aspects of weed ecology (community composition, management and environmental effects and within-field distributions) and use a range of statistical techniques (canonical correspondence analysis, redundancy analysis and generalised linear mixed models) to demonstrate the utility and versatility of the AWME database. We demonstrate that (i) the standardisation of abundance data to a common measure, before the analysis of the combined dataset, has little impact on the outcome of the analyses, (ii) the increased extent of environmental or management gradients allows for greater confidence in conclusions and (iii) the main conclusions of analyses done at different spatial scales remain consistent. These case studies demonstrate the utility of a Europe-wide weed survey database, for clarifying or extending results obtained from studies at smaller scales. This Europe-wide data collection offers many more opportunities for analysis that could not be addressed in smaller datasets; including questions about the effects of climate change, macro-ecological and biogeographical issues related to weed diversity as well as the dominance or rarity of specific weeds in Europe.     

Can a specialist parasite species of a widespread and common host species be rare? The case of Spinitectus inermis (Nematoda: Cystidicolidae) in eels Anguilla anguilla

The claim by many authors that Spinitectus inermis (Zeder, 1800), a narrowly specific parasite of European eels Anguilla anguilla (L.), is a rare species is considered at three levels: its geographical range, its frequency of occurrence compared to other eel parasites and its relative abundance in component communities. The parasite is widely distributed in freshwater throughout the European range of the eel but its occurrence is erratic and unpredictable, being known from only 8 countries. Surveys of eel parasites in the United Kingdom and in Continental Europe show that it is present in only 13% of British and 29% of continental localities. This satisfies one of the criteria for rarity. When present, its prevalence ranges from 1.8% to 43.3%, so it can be considered rare in some localities but in a few it may be common and on occasion it may be the dominant species in the gastro-intestinal community. Populations of S. inermis are almost always characterised by high levels of overdispersion, even at low prevalence. The species also displays an ability to colonise a locality following introduction there. Overall it meets many of the criteria of a rare species including a restricted distribution and a low frequency of occurrence and so it can be considered to exhibit diffusive rarity.     

Sex-specific probing behaviour of the carrot psyllid <Emphasis Type="Italic">Bactericera trigonica</Emphasis> and its implication in the transmission of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter solanacearum’

‘Candidatus Liberibacter solanacearum (Lso)’ is a pathogen of Solanaceae but also causes serious physiological disorders in carrots and celery (Apiaceae). In carrots, this pathogen is transmitted by the psyllids Bactericera trigonica and Trioza apicalis. How vector sex influences Lso transmission has not been yet elucidated. Here we report the probing behaviours of male and female B. trigonica and their impact on Lso titre transmitted, percentage of transmission, and symptoms produced on carrots when Lso is transmitted by males or females of B. trigonica. Vector sex affected the inoculation of Lso; our results suggest that females might inoculate higher Lso titres than males. However, the percentage of transmission was not affected by vector sex at a density of one or eight psyllids per plant. The number of yellow leaves and root weight were not different when Lso was transmitted by males or females at either of the psyllid densities tested, except for groups of females whose Lso transmission resulted in a higher number of yellow leaves than did Lso transmitted by groups of males. Electrical penetration graphs (EPG) showed that the proportion of individuals who reached phloem tissues was similar for males and females. However, EPGs also showed that females probed more times, ingested longer from phloem sieve elements and reached phloem tissues more frequently than did males during an 8-h inoculation access period (IAP). Our study shows that differences in probing behaviours between males and females of B. trigonica could modulate how Lso is inoculated by psyllids. These results highlight the importance of taking sex into consideration in psyllid studies of probing behaviour and bacterial transmission.     

Activity of <Emphasis Type="Italic">ß</Emphasis>-1,3-glucanase and <Emphasis Type="Italic">ß</Emphasis>-1,4-glucanase in two potato cultivars following challenge by the fungal pathogen <Emphasis Type="Italic">Alternaria solani</Emphasis>

Early blight of potato, caused by Alternaria solani, is a ubiquitous disease in many countries around the world. Our previous screening of several Iranian potato cultivars found that variation in resistance exists between two cultivars: ‘Diamond’ and ‘Granula’. Cultivar Diamond is more resistant to multiple isolates of A. solani when compared to cv. Granula. Furthermore, we have found that different pathogen isolates have varying degrees of infection. We monitored the activities of two pathogen-related (PR) glucanase proteins in Diamond and Granula in response to two isolates of A. solani with different degrees of virulence. ß-1,3-glucanase and ß-1,4-glucanase activities were recorded in healthy and diseased leaves of potatoes up to 10 days after inoculation. Their activities were found to be higher in diseased leaves when compared to those of uninfected leaves. Our data suggest that significantly reduced activities of theses enzymes in potato could be related to a lower degree of resistance or an increased ability of a more aggressive isolate to suppress PR protein expression.     

False codling moth,Thaumatotibia leucotreta (Meyrick) a new threat to horticulture industry: Stakeholders’ perspectives on the status,impact and management in Kenya

Journal of Plant Diseases and Protection - False codling moth (FCM) has emerged as a major constraint to the production of horticultural crops in Kenya and is currently the leading cause of...     

Biological control of the millet head miner Heliocheilus albipunctella in the Sahelian region by augmentative releases of the parasitoid wasp Habrobracon hebetor: effectiveness and farmers’ perceptions

On-farm augmentative releases of the parasitoid Habrobracon hebetor (Say) for controlling the millet head miner (MHM) Heliocheilus albipunctella (de Joannis) were tested in Burkina Faso, Mali and Niger from 2007 to 2009. In addition, a survey of farmers’ perceptions of insect pests, with particular focus on MHM, and the biological control program (BCP) was carried out. There was a significant increase of MHM parasitization rate after the releases, with up to 97% mortality. The survey on farmers’ perceptions revealed a fair knowledge of the MHM and the ability of farmers to describe the pest and the damage it caused. Farmers claimed that the biocontrol agent H. hebetor is effective and perceived a significant gain in grain yield due to this control strategy. Implications of these findings for a large extension of the MHM biocontrol program are discussed.