Methodology of selection of lemon clones for tolerance to Mal Secco (Phoma Tracheiphila)

Leaf and stem inoculations of lemon seedlings withPhoma tracheiphila resulted in severe infection and did not reflect satisfactorily the reaction of lemon cultivars to natural mal secco infection in the field. A tolerance rating by stem inoculation was closer to known field performance of lemon cultivars. The tolerance was affected by the rootstock, withCitrus volkameriana conferring a higher tolerance than Sour orange (C. aurantium) or Rough lemon (C. jambhiri). The field inoculation test gave ratings of tolerance closest to natural infection data; Monachello was the only tolerant cultivar, and Santa Teresa showed slight tolerance.     

Effect of mal secco toxin on lemon leaf cells

Leaves of Rough lemon (Citrus jambhiri) were inoculated withPhoma tracheiphila or treated with mal secco toxin. The ultrastructural changes in toxin-treated leaves resembled closely those infected by the pathogen, being characterized by separation of the plasmalemma from the cell wall, vesiculation of plasmalemma, disruption of the chloroplast membrane, disorganization of thylakoids, and increase in size and number of osmiophilic droplets in the chloroplasts. The rate of photo-synthetic CO₂ fixation by mesophyll protoplasts was reduced in the presence of the toxin. The toxin induced agglutination of mesophyll protoplasts of lemon only in the presence of an antiserum to the toxin. Agglutination of protoplasts was independent of the biological activity of the toxin and was inhibited by Dmannose or after mild base hydrolysis of the toxin.     

Fusaric Acid Production by Fusarium Oxysporum f.sp. lilii and its Role in the Lily Basal Rot Disease

Fusarium oxysporum f.sp. lilii (Fol), the causal agent of lily basal rot, produced fusaric acid (FA) in aseptic culture. This toxin induced phytotoxicity symptoms on in vitro-grown lily bulblets of two different cultivars: the Fol-susceptible cultivar was more sensitive to the toxin than the Fol-resistant cultivar. When cultured in the presence of FA, the Fol-susceptible cultivar showed a greater tendency to accumulate FA within its tissues than the Fol-resistant cultivar. The polyphenol oxidase activity of the bulblets was inhibited by 1mmolL^–1 FA in both the cultivars, while at lower FA concentrations the enzyme activity increased only in the Fol-susceptible cultivar. Peroxidase showed a steady activity at the 1mmolL^–1 FA concentration in both the cultivars, while at lower FA dosages its activity increased. Within the Fol-infected in vivo tissues of both the lily cultivars, FA was detectable only in traces. The role of this toxin in the lily basal rot disease seems therefore to be of marginal importance.     

Susceptibility of the carob moth,Ectomyelois ceratoniae,toBacillus thuringiensis

A 1% concentration ofBacillus thuringiensis wettable power (containing 16,000 IU/mg), applied at a rate of 48,000 IU/cm², killed 95% of 4th-instar larvae of the carob moth,Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae), after 66 h and 100% after 85 h of exposure in laboratory tests. The mortality caused by a 0.5% concentration (24,000 IU/cm²) was significantly lower and presumably inadequate for practical application against this pest.     

Management of wheat blast with synthetic fungicides,partial resistance and silicate and phosphite minerals

Field trials conducted on a yellow-red latossol (pH 6.0), replicated in 2010 and 2011, sought to examine the effect of silicon, phosphite minerals, synthetic fungicides and genetic resistance for wheat blast management (Magnaporthe grisea) in Central Brazil. Disease intensity was measured on cvs. BRS 264 and BR18 subjected to the following Si treatments: pre-plant furrow application of Ca & Mg silicate (300 kg ha^-1); post-plant scattered application of Ca & Mg silicate on top of the soil (1 ton ha^-1); multiple foliar SiO₂ applications (30 g l ^-1); and non-treated control. Blast incidence and severity were scored. Further experiments were conducted on cv. BR-264, for examination of the effect of potassium phosphite and synthetic fungicides on wheat blast intensity, with the following treatments: K₂HPO₃ (1ml l ^-1); epoxinazole + pyraclostrobin (700 ml ha^-1); tebuconazole (600 ml ha^-1); tebuconazole + trifloxystrobin (750 ml ha^-1); and non-treated control. In 2010, disease intensity was lower than in 2011. In the silicate experiments, disease was significantly lower when plants were treated with foliar or furrow silicate. Si applications significantly reduced disease in BRS-264. While BR-18 consistently demonstrated lower disease levels, cv. BRS-264 generally responded more markedly to silicon applications. In the phosphite/fungicide experiment of 2010, all treatments reduced disease when compared with the control, and in 2011 phosphite efficiency was not significantly different from some fungicide treatments. Synthetic fungicides demonstrated an average blast control of 55% by severity values. Yields were increased in the phosphite-treated plots (by 9–80%), in the Si treatments (by 26–92%), and more so, and more consistently, with synthetic fungicides (by 90–121%). Combined results of all field studies, carried out under environmental conditions highly conducive to disease, indicated that control of wheat blast necessitates the joint integration of several alternatives for efficient disease management.     

Pythium pod rot reduction in peanuts,as affected by breeding for resistance and by disease level

The introduced cultivar ‘Schwarz-21’, a source of resistance, was crossed with the large-podded local cultivar ‘Virginia Bet Dagan No. 4’. Selection of the progeny for larger pods led to reduced resistance levels. The combination of intermediate resistance and use of the inexpensive biocide metham (Vapam) led to low pod rot incidence.     

<Emphasis Type="Italic">Alternaria alternata</Emphasis> apple pathotype (<Emphasis Type="Italic">A. mali</Emphasis>) causes black spot of European pear

A disease caused by Alternaria alternata occurred on the leaves of European pear cultivar Le Lectier in Niigata Prefecture, Japan, and was named black spot of European pear. In conidial inoculation tests, the causal pathogen induced not only small black lesions on the leaves of European pear cultivar Le Lectier, but severe lesions on the leaves of apple cultivar Red Gold, which is susceptible to the A. alternata apple pathotype (previously called A. mali) causing Alternaria blotch of apple. Interestingly, the apple pathotype isolate showed the same pathogenicity as the European pear pathogen. HPLC analysis of the culture filtrates revealed that A. alternata causing black spot of European pear produced AM-toxin I, known as a host-specific toxin of the A. alternata apple pathotype. AM-toxin I induced veinal necrosis on leaves of Le Lectier and General Leclerc cultivars, both susceptible to the European pear pathogen, at 5?×?10^?7 M and 10^?6 M respectively, but did not affect leaves of resistant cultivars at 10^?4 M. PCR analysis with primers that specifically amplify the AM-toxin synthetase gene detected the product of expected size in the pathogen. These results indicate that A. alternata causing black spot of European pear is identical to that causing Alternaria blotch of apple. This is the first report of European pear disease caused by the A. alternata apple pathotype. This study provides a multiplex PCR protocol, which could serve as a useful tool, for the epidemiological survey of these two diseases in European pear and apple orchards.     

Identification and characterization of Phoma tracheiphila mutants impaired in pathogenicity following Agrobacterium-mediated mutagenesis

Mal secco disease, caused by the pathogenic fungus Phoma tracheiphila, is a devastating disease of susceptible citrus species, especially lemon. To study the molecular interactions between the pathogen and its host, a method for identifying the genes involved in pathogenicity is needed. This work describes the transformation of P. tracheiphila phialoconidia by Agrobacterium tumefaciens, and the generation of mutated P. tracheiphila isolates exhibiting reduced virulence on rough lemon seedlings. A rapid, replicable, and reliable method for screening P. tracheiphila mutants to assess their virulence by using rough lemon seedlings was developed. Among 2263 transformants obtained, three were non-virulent and 43 displayed reduced virulence. In addition, one of the transformants, which exhibited virulence similar to that of the wild type, was used for in planta visualization of the fungus progression through the plant xylem. To our knowledge, this is the first report of A. tumefaciens-mediated transformation of P. tracheiphila, and subsequent screening of the transformants to identify non-virulent mutants.     

Potential use of Eucalyptus globulus essential oil against Phytophthora colocasiae the causal agent of taro leaf blight

This study was carried out to determine the antimicrobial activity of essential oil derived from leaves of eucalyptus (Eucalyptus globulus) against Phytophthora colocasiae, the causal agent of taro leaf blight (TLB). Essential oil was obtained by Clevenger-type water distillation. The major compounds in this essential oil were identified using gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS). Antimicrobial activity of the essential oil was tested in vitro against mycelial growth, sporangia and zoospores germination of P. colocasiae. Additionally, in situ tests were conducted on detached healthy taro leaves discs and evaluating necrosis symptoms of TLB were assessed. Results of the chemical composition of the essential oil analysis showed that, 1.8-cineole (26.4 %), α-pinene (14.1 %) and p-cymene (10.2 %) are the most abundant compounds. In addition, four components could be identified in noticeable amounts (18.1 % in the total): regulator G1/G2 and its derivatives as well as flavesone, a regulator G3 derivative. G is a generic term for a family of 2,3-dioxabicyclo[4,4,0] decane system growth regulators. Here, G-regulators and derivatives are described for the first time in E. globulus. Antimicrobial activity of the essential oil was recorded with total inhibition of mycelia growth and sporangia germination at 0.625 mg/ml, while the complete inhibition of zoospores germination was recorded at 0.156 mg/ml. In situ results showed that essential oil completely inhibited the appearance of disease symptoms, necrosis development and sporulation at 3.5 mg/ml. These results demonstrated that, the essential oil of Eucalyptus globulus has high ability to inhibit the development of P. colocasiae, and might be used for controlling TLB.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Resistance mechanisms and risk assessment regarding indoxacarb in the beet armyworm,Spodoptera exigua

The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), is a worldwide polyphagous pest with a strong ability to develop resistance. After 12 generations of selection by indoxacarb, a resistant strain (RR-indox) was obtained with a 240.04-fold resistance ratio compared with the susceptible strain (WH-SS), which was derived from the Wuhan Institute of Vegetable Science. The LC₅₀ for the susceptible strain was 0.23 mg l ^-1 and it increased to 55.21 mg l ^-1 after 12 selected generations. The estimated realized heritability (h²) of the RR-indox strain was 0.25. The number of generations required for a 100-fold increase in LC₅₀ was estimated to be nine under the 90% lethal dose. The inhibitors piperonyl butoxide (PBO), triphenyl phosphate (TPP), and diethylmeleate (DEM) had synergistic ratios of 0.87-, 0.31- and 0.36-fold in RR-indox, and 0.51-, 0.09- and 0.12-fold in WH-SS, respectively. A 3.75-fold increased level of activity of glutathione S-transferase was found in RR-indox compared with WH-SS, whereas a 1.99-fold higher activity level of carboxylesterase was observed. No significant differences in the cuticular penetration rate were found between RR-indox and WH-SS. A DNA fragment of 257 bp length of the IIS6 region of the voltage-gated sodium channel gene was amplified and sequenced from both RR-indox and WH-SS. An amino acid substitution from leucine (CTT) in WH-SS to phenylalanine (TTT) in RR-indox was observed at site 1014. These results show the resistance mechanisms of S. exigua to indoxacarb to be associated with glutathione S-transferase, carboxylesterase and a Leu-1014-Phe mutation.     

Pyrethroid synergism and prevention of emergence inTribolium castaneum andMusca domestica vicina by the insect growth regulator RO 13-5223

Ethyl [2-(4-phenoxyphenoxy)ethyl] carbamate (RO 13-5223) at a dietary concentration of 100 mg kg^-1 synergized the toxicity of thetrans- andcis-isomers of permethrin and cypermethrin in inhibiting the growth (measured as gain in larval weight) ofTribolium castaneum andMusca domestica vicina. With both species the synergism factor forcis-cypermethrin with 100 mg kg^-1 synergist was 1.5- to twofold for RO 13-5223 and about fourfold for piperonyl butoxide. Synergism was more pronounced with first instar than with fourth instarT. castaneum larvae. Methoprene was not a pyrethroid synergist withT. castaneum larvae, so the synergistic effect of RO 13-5223 appears to depend on its structural features and not its insect-growth-regulator activity. Joint application of RO 13-5223 and pyrethroids resulted in a dual effect on bothT. castaneum andM. domestica: increased inhibition of larval growth due to pyrethroid synergism, and progeny suppression — expressed by larval and pupal mortality — due to RO 13-5223 juvenilizing activity.     

Shallot latent virus,a new carlavirus

A new carlavirus, apparently omnipresent in shallot (Allium ascalonicum) without causing symptoms, is described as shallot latent virus. It has also been detected in naturally infected onion (A. cepa) and leek (A. porrum). The virus was easily transmissible in sap and could be transferred withMyzus ascalonicus. Infection after inoculation was symptomless in onion, leek,A. fistulosum andA. jailae. Chenopodium album, C. amaranticolor andC. quinoa reacted with local lesions.A. neapolitanum andA. schoenoprasum and 20 other plant species were immune. Dilution end-point was 10⁴–10⁵, thermal inactivation at ca. 80°C and ageing in vitro 8–11 days. Purification by molecular sieving on Sephadex G-200 followed by equilibrium density-gradient centrifuging in CsCl was successful. Sedimentation coefficient was 147.5 S, bouyant density 1.313 g/cm³ and molecular mass of protein subunits 23 200 dalton. With the antiserum (titre 1024) distant serological relationships to some carlaviruses were determined. No inclusion bodies were observed with the light microscope. With the electron microscope a high concentration of straight or slightly curved particles with a normal length of 650 to 652 nm could easily be detected in crude sap and in purified preparations.     

Enzyme-linked immunosorbent assay (ELISA) for the detection of potato viruses A and Y in potato leaves and sprouts

With the enzyme-linked immunosorbent assay (ELISA) potato virus A (PVA) could be detected reliably in potato sprouts, especially when these were young and sappy. The detection of this virus in leaves of glasshouse-grown potato plants was less reliable. The tobacco veinal necrosis strain of potato virus Y (PVY^N) was readily demonstrated in foliage of glass-house-grown potato plants using an antiserum to this strain. Plants infected with the common strain (PVY^O) did not react in ELISA with this antiserum. In young sappy sprouts, using the PVY^N antiserum, PVY^N could be detected reliably when samples with PVY^O were excluded, as the reaction of samples infected with the latter virus was intermediate between PVY^N-diseased and PVY-free samples. PVY was also detected in plants inadvertently infected during the experiments.     

Drain of nutrients imposed when Aphis sambuci and a. fabae feed on the inflorescence of Yucca flaccida,and the amounts retained by the aphids

For the production of 1 g dry weight of aphids about 10 g dry weight (55 ml) of sieve tube sap ofYucca flaccida is required, provided all N taken up by the aphids is retained by them. The production capacity of an averageYucca leaf was calculated at 4 mg dry weight of aphids per day or 30 g per cm² leaf area per day. Compared with N only about 30% of the P, K, Na, Mg, and Ca ingested by the aphids is retained by them, apparently in the same mutual ratios as these elements occur in the sieve tube fluid.Samenvatting Bij een aangenomen 100% benutting van de door luizen uit zeefvaten opgenomen N, is voor de ontwikkeling van 1 g drooggewicht vanA. fabae enA. sambuci ca. 10 g droog zeefvatensap nodig (55 ml). De produktiecapaciteit van eenYucca blad van gemiddelde grootte werd berekend op 4 mg droge luis per dag, overeenkomend met ca. 30 g per cm² bladoppervlak.Vergeleken met die van de N is de benutting van de door de luizen opgenomen hoeveelheden P, K, Na, Mg, en Ca slechts ongeveer 30%; dit gebeurt in ongeveer dezelfde onderlinge verhoudingen als waarin deze elementen in het zeefvatensap aanwezig zijn (Tabel 1).     

Comparative toxicity of several insecticides to eggs,larvae and adults of the Egyptian cottonworm,Spodoptera littoralis,in laboratory trials

Insecticides commonly used in cotton fields in Israel against lepidopterous pests were tested against eggs, as well as against 2nd-instar larvae and adults raised from eggs ofSpodoptera littoralis (Boisduval) collected in cotton fields in the Bet She’an Valley. Methomyl, chlorpyrifos, methidathion, monocrotophos, ethyl parathion, and methyl parathion were effective against eggs even at low doses, profenofos and phosfolan were less active, and azinphos-methyl was ineffective. The doses needed for 90% kill (LD ₉₀ ) of the 2nd-instar larvae were 8.5, 35, 280, 1300 and 3400 g a.i./1000 m ² for chlorpyrifos, methomyl, profenofos, methyl parathion and ethyl parathion, respectively; monocrotophos was inactive against 2nd-instar larvae even at relatively high doses. The LD ₉₀ of adults was reached with 16, 32, 1700 and 6100 ga.i./l000 m² of chlorpyrifos, methomyl, ethyl parathion and profenofos, respectively. Only chlorpyrifos and methomyl gave successful control of all three stages of the insect tested, at doses close to those generally used with aerial applications.     

Enhancement of wheat tolerance to triallaic with the safener MON 5501

The triallate tolerance of wheat (Triticum aestivum L.) cultivars Marius and Mexicali was determined under growth-chamber conditions. Mexicali was found to tolerate triallate at levels about fourfold higher than Marius. The susceptible wheat cultivar was protected against triallate by seed treatment with MON 5501. The herbicide concentration in the aerial part of the plants was determined by gas chromatography. Triallate levels were similar in both cultivars treated with 0.5 mg 1^?1 of triallate. The safener did not affect the triallate content per plant in the susceptible wheat cultivar treated with 1 mg 1^?1 of herbicide. Augmentation de la tolerance du blé au triallate avec le phytoprotecteur MON 5501 La tolerance au triallate des cultivars de ble Marius et Mexicali a été déterminée en chambre climatique. Mexicali s'est avéré 4 fois plus tolérant que Marius. Le cultivar de blé sensible a été protege du triallate par un traitement des grains avec MON 5501. La concentration en herbicide dans la partie aérienne des plantes a été determined par chromatographie gazeuse. Les taux de triallate ont été equivalents chez les 2 cultivars traites avec 0,5 mg l^?1 de triallate. Le phytoprotecteur n'a pas affecté lateneur en triallate par plante chez le cultivar sensible traite avec 1 mg 1^?1 d'herbicide. Verbesserung der Toleranz von Weizen gegenuber Triallat mil dem Antidot MON 5501 Die Triallat-Toleranz der Weizensorten ‘Marius’ und ‘Mexicali’ wurde im Phytotron bestimmt. ‘Mexicali’ war etwa 4mal toleranter als ‘Marius’. Die empfindliche Weizensorte wurde durch Beizung mit MON 5501 gegen Triallat geschützt. Die Herbizidkonzentration in den oberirdischen Pflanzenteilen wurde gaschromatographisch bestimmt Der Wirkstoff-Gehalt war in beiden mit 0,5 mg 1^?1 Triallat behandelten Sorten ahnlich hoch. Das Antidot hatte keinen Einfluβ auf den Triallat-Gehalt der empfindlichen Weizensorte, die mit 1 mg 1^?1 behandelt worden war.     

Toxigenic Fusarium Species of Liseola Section in Pre-harvest Maize Ear Rot, and Associated Mycotoxins in Slovakia

The occurrence of Fusarium species of Liseola section and related toxins was investigated for two years (1996 and 1998) on maize ear rot samples collected in the most important areas for maize growing in Slovakia. The species most frequently isolated was F. verticillioides, followed by F. proliferatum in 1996 and F. subglutinans in 1998. Most of the strains belonged to mating populations A, D, and E of the teleomorph Gibberella fujikuroi. Fusarium graminearum was also frequently recovered in both the years of investigations. Toxin analysis of maize ears showed that most of the samples (21 out of 22) were contaminated with at least one toxin. In particular, the concentration of fumonisin B₁, and fumonisin ₂ was up to 26.9 and 5.1gg^-1, respectively in 1996, and up to 12.1 and 6.3gg^-1, respectively in 1998. Beauvericin was detected only in one sample in 1996. Seven samples in 1996 were contaminated by fusaproliferin up to 8.2gg^-1, but just traces of the toxin were found in one sample in 1998. All 29 strains of F. verticillioides, two of three strains of F. proliferatum and none of eight F. subglutinans strains isolated from samples produced fumonisin B₁ in culture on whole maize kernels (0.1–5646 and 940–1200ugg^-1, respectively). Two strains of F. subglutinans and two of F. proliferatum produced beauvericin (up to 65 and 70gg^-1, respectively). Ten strains of F. verticillioides produced beauvericin: 9 strains produced a low amount (up to 3gg^-1), while only one of them produced a high level of toxin (375gg^-1). Fusaproliferin was produced by two F. proliferatum strains (220 and 370gg^-1), by seven F. subglutinans (20–1335gg^-1) and by three F. verticillioides (10–35gg^-1). This is the first report on fusaproliferin production by F. verticillioides, although at low level.     

<Emphasis Type="Italic">Fusarium</Emphasis> head blight incidence and detection of <Emphasis Type="Italic">Fusarium</Emphasis> toxins in wheat in relation to agronomic factors

We investigated incidences of Fusarium head blight (FHB) and concentrations of six mycotoxins (deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol, T-2 toxin, HT-2 toxin and zearalenone) in wheat from 2010 to 2013. Field trials were conducted at the Experimental Station of Cultivar Testing in Chrz?stowo, Poland (53^o11’N, 17^o35’E). We examined the effects of four agronomic factors, including pre-crop type (corn, sugar beets and wheat), date of sowing (late autumn: November 8–December 9 or spring: March 29–April 19), fungicidal application (untreated or treated with two applications) and cultivar (Monsun, Cytra), on FHB index (FHBi) and mycotoxin levels in order to minimize the risk of wheat grain contamination by mycotoxins via integrated pest management methods. The dominant Fusarium species observed on wheat heads were F. culmorum, F. avenaceum (Gibberella avenacea) and F. graminearum (Gibberella zeae), at 21.1%, 17.2% and 7.1%, respectively. A monthly rainfall sum of 113.9 mm and a relatively low air temperature (monthly average 15.5 °C) resulted in the highest FHBi in untreated wheat (25.1%). Agronomic factors crucial for the FHB incidence were the pre-crop, fungicidal treatments and cultivar selection. In wheat planted after wheat or corn, the FHBi was higher compared with a pre-crop of sugar beet. A double application of fungicides at BBCH 30–32 with prothioconazole and spiroxamine and at a BBCH 65 with fluoxastrobin and prothioconazole effectively reduced the FHBi and mycotoxin concentrations, respectively, in grain. The cultivar ‘Cytra’ had a greater FHBi (10.4%) than ‘Monsun’ (4.6%), and grain infestations by Fusarium species were also greater in ‘Cytra’, at 16.5%, than in ‘Monsun’, at 11.2%. Untreated cv. Cytra grown after corn in spring produced grains with the highest amounts of the mycotoxins, deoxynivalenol, 3-acetyldeoxynivalenol, zearalenone and HT-2 (605, 103, 17.5 and 5.53 μg/kg, respectively). Total mycotoxin levels in wheat were correlated with five determinants: duration of the period between the end of flowering and the beginning of kernel abscission, FHBi, F. culmorum isolation, G. zeae isolation and Fusarium ratio (FR) as a % of total mould isolations. Although, the mean concentration of mycotoxins in grain did not exceed the maximum permissible values for unprocessed wheat our study suggests necessity to monitor and mitigate FHB risk for susceptible cultivars, when wheat spring sowing follows corn or wheat.     

Performance ofAphis Fabae on Chocolate Spot Disease-Infected Faba Bean Plants

The effect of chocolate spot disease (incited byBotrytis fabae) on the host plant quality of two cultivars of faba beans (Vicia faba) for the black bean aphid (Aphis fabae), was investigated under greenhouse conditions. Faba bean cultivar Bolero is resistant to the aphid, whereas cv. Diana is susceptible. On healthy leaves of cv. Bolero, aphids completed their development one day later than the aphids reared on infected leaves of this cultivar and those which matured on healthy or infected leaves of cv. Diana. Mean weight of apterous virginoparae, mean relative growth rate, and intrinsic rate of natural increase were enhanced if the aphids were reared on infected leaves of either cultivar. Mean total progeny per female increased only on infected leaves of cv. Bolero, but not on cv. Diana.