Synthetic pyrethroids and avermectin for controlling the grapevine pestsLobesia botrana,Cryptoblabes gnidiella andDrosophila melanogaster

Field treatments in a vineyard with 0.015 or 0.01% a.i. of cypermethrin, fenvalerate, fenpropathrin or AC-222,705 were more efficient in controlling the grape-berry moth (Lobesia botrana Schiff.) and the honeydew moth (Cryptoblabes gnidiella Mill.) than four standard treatments consisting of two with 0.05% a.i. fenitrothion and two with 0.075% a.i. diazinon. In pyrethroid-treated plots, infestation at the end of the trials ranged between 2.5 and 12%, compared with 21% in the standard treatment plots and 34% in the untreated plots. Cypermethrin, fenpropathrin and AC-222,705 exhibited similar field activity, while that of fenvalerate was somewhat lower. Under laboratory conditions, cypermethrin at 0.005 and 0.01% a.i. was significantly more potent than fenvalerate, fenpropathrin and AC-222,705; at a higher concentration, 0.015% a.i., all pyrethroids were highly active, with mortality ranging between 75 and 95%. Under laboratory conditions the vinegar fly (Drosophila melanogaster Meig.) was in general more susceptible to pyrethroids than was the grape-berry moth. Cypermethrin and AC-222,705 at 0.005% a.i. and avermectin at 0.0035% a.i. were potent compounds against the vinegar fly and more active than fenvalerate and fenpropathrin.     

Efficacy of <Emphasis Type="Italic">Beauveria Bassiana</Emphasis> for the Management of Economically Important Wireworm Species (Coleoptera: Elateridae) in Organic Farming

Wireworms, the larvae of click beetle species Agriotes lineatus, A. obscurus and A. sputator are serious pests for several field crops. They are considered severe pests of potato tubers and the damages caused by them can be resulted a significant loss especially in organic crop production. Since synthetic insecticides are prohibited in Organic Farming; biological control methods have to be used in organic crop production. In the current study naturalis Beauveria bassianaa strain ATCC 74040 was used both under laboratory and field conditions using wheat and potato crops as a food source respectively. Fungus showed a significant mortality in high number of wireworms boxes (50%) compared to low number of wireworms (17%) and untreated boxes (13%) respectively. However, seed germination showed no effect in all three categories. Field data have shown mixed results when B. bassiana has been applied in a variety of application methods. Maximum infestation (3.99%) was recorded in untreated plots; while significantly lower damage (1.11%) was recorded in whole surface treated plots. During first year all the treatments were significantly different from each other; however, no significant differences were noted between furrows and whole surface applications but were different from control treatment during second year of experimentation. The results showed that the biological control of wireworms by using entomopathogenic fungi, such as B. bassiana is a promising target specific option without disturbing the other communities in the soil.     

Inactivation of sclerotia of Rhizoctonia solani on potato tubers by Verticillium biguttatum,a soil-borne mycoparasite

Experiments in the laboratory and on farms with potato tubers in storage are described in which sclerotia ofRhizoctonia solani were inactivated after inoculation of infected tubers with a suspension of conidia and hyphal fragments ofVerticillium biguttatum. Sclerotia on freshly harvested tubers can be killed in a period of six to eight weeks, provided that (1) a direct contact between sclerotia and conidia ofV. biguttatum is obtained, (2) the temperature during the storage period is at least 15 °C, but preferably closer to 20 °C during the first weeks, and (3) the relative humidity of the air between the tubers is at least 99%. Seed tubers are only certified as export quality if the infection withR. solani, visible as sclerotia on the tubers, is assessed as below a specified incidence. To restore the economical value of tubers with many sclerotia, living sclerotia can be inactivated byV. biguttatum. However, also dead sclerotia have to be removed, as dead and living sclerotia cannot be distinguished visually by inspectors. A satisfactory way to remove dead sclerotia from tubers has not yet been found.     

Methyl bromide and PCNB for sclerotium crown rot control in iris

Methyl bromide (MB) at rates of 500, 1000 and 1500 kg/ha, Terraclor 75 WP (PCNB) at 150 and 300 kg/ha, and combinations of the two, were studied for control ofSclerotium rolfsii prior to iris cultivation. Sclerotia buried 10 cm deep in soil were all killed by MB at 500 kg/ha; at greater depths higher doses were required. Bulbs harvested from PCNB- and PCNB + MB-treated plots were healthy; 75% of the bulbs in control plots were infected at harvest. When MB was used alone, the soil became re-infested (2–6% diseased plants). Bromide toxicity, correlated with the MB dose applied, appeared 41/2 months after planting; leaves yellowed and senesced prematurely. MB treatments also reduced bulb size, and residual phytotoxicity was found when the bulbs from treated plots were planted in the following year.     

Inhibitory effects of some insect growth regulators on developmental stages,fecundity and fertility of the Florida wax scale,Ceroplastes floridensis

Four juvenile hormone analogs (JHAs), fenoxycarb. Pro-drone, R-20458 and dofenapyn, and three benzoylphenyl urea molt-inhibiting compounds (MICs), teflubenzuron, triflumuron and hexaflumuron, were evaluated in the laboratory at two concentrations (5 and 50 ppm) as to their effect on the Florida wax scale,Ceroplastes floridensis Comstock. In general, when the first nymphal stages were treated, the number of adults on treated guava plants at the end of the first generation was clearly reduced in comparison with that observed on untreated plants. The JHAs fenoxycarb and R-20458 arrested the development of the insect and no adults emerged at the end of the first generation. With 50 ppm of the JHA Pro-drone only 5.2% of the nymphs developed and transformed into adults. Triflumuron was superior to the other insect MICs in hampering development, as was dofenapyn. The adults emerging at the end of the first generation were used as parental scales for the next generation. Delayed adverse effects were observed on female fecundity and egg hatchability. There was a significant difference between the egg numbers laid by the females in the treatments and the control, and also between the different IGRs. No eggs hatched with dofenapyn and egg hatchability was 46% for teflubenzuronvs 88% for the control. Furthermore, in contradistinction to the control, insects on treated plants deposited only small amounts of wax in an irregular formation.     

Serological recognition of Streptomyces species causing scab on potato tubers

Antisera were prepared against extracts of two tyrosinase-positiveStreptomyces spp., one of which caused a “deep” and the other a “russet” scab. Tyrosinase-positiveStreptomyces isolates not reacting with either of these antisera proved to be nonpathogenic to potato tubers, with few exceptions only. Not all isolates reacting with one or both antisera, however, were pathogenic and so all the serological positive ones had to be tested for pathogenicity to potato tubers. To obtain this relative specificity the antisera had to be absorbed with an extract of a non-pathogenic tyrosinase-positive isolate.     

Potato blackleg: Epidemiology,host-pathogen interaction and control

Blackleg is caused byErwinia carotovora subsp.atroseptica (Eca) andE. chrysanthemi (Echr) in cool and hot climates respectively. The bacteria are opportunistic pathogens and rely on their strong pectolytic character to infect plants when conditions favor their multiplication. Blackleg is a seedborne disease and the bacteria can survive in a quiescent form in lenticels and wounds during storage. The contaminated mother tuber and not the blackleg plant is the main source of progeny tuber contamination. Other sources of the pathogen are airborne (insects and aerosols) erwinias deposited on leaves and from there to the soil and progeny tubers, and erwinias in rotting tubers smeared into wounds incurred during mechanical crop handling.Most seed tubers are contaminated but blackleg incidence is related to seed contamination level modulated by soil water status. Competitiveness of the erwinias in the rotting mother tuber is affected by temperature, Eca is favored at <25°C and Echr at higher temperatures. The ubiquitousE. carotovora subsp.carotovora apparently fails to compete successfully with the other erwinias and saprophytic pectolytic bacteria in mother tubers and therefore does not cause blackleg.Disease control measures are based on avoiding tuber contamination by cultural means (early harvesting), reducing tuber contamination level (dry storage and hot water treatment) and planting ‘clean’ seed identified by quantifying tuber contamination rather than by visual crop inspection. Finally, recently identified highly resistant, even under anaerobic conditions, wildSolanum spp. could be used to breed for resistant cultivars by conventional methods or by genetic engineering.     

Potential biopesticides for crucifer flea beetle, <Emphasis Type="Italic">Phyllotreta cruciferae</Emphasis> (Coleoptera: Chrysomelidae) management under dryland canola production in Montana

The crucifer flea beetle, Phyllotreta cruciferae (Goeze), is an economically important and dominant pest of canola (Brassica napus L) in the Northern Great Plains of the USA. The current flea beetle management strategy is based on using synthetic chemical treated seeds and if necessary, foliar spray of chemicals at canola seedlings in early spring for targeting adult population. However, there is an increasing demand for development of alternative management strategies for P. cruciferae pertaining to concerns over the development of resistance to synthetic insecticides and non-target effects on pollinators and other beneficial insects. Replicated field trials were conducted to test the efficacy of several commercially available biopesticides including Entrust® (spinosad), entomopathogenic nematode Steinernema feltiae?+?Barricade® (polymer gel 1%), Aza-Direct® (azadirachtin), Pyganic 1.4® EC (pyrethrin), Grandevo® SC (Chromobacterium subtsugae), Venerate® XC (Heat killed Burkholderia sp. strain A396 as seed treatment and foliar application) and Gaucho® (imidacloprid) (chemical check) for the P. cruciferae management at two locations (Conrad and Sweetgrass) of Montana in 2016. Biopesticide products were evaluated based on canola leaf area injury ratings and seed yield levels. Although, there was no clear trend of canola yield increase, selected biopesticide treatments were effective in maintaining low leaf area injury ratings as compared to untreated control. Entrust was able to maintain low leaf area injury ratings (8.5–14.5%) when compared to untreated control (16.0–21.4%) at both the locations. Entomopathogenic nematodes, Steinernema feltiae?+?Barricade® and Venerate® applied as foliar treatments maintained significantly lower feeding injury pressure at Sweetgrass (11.8%) and Conrad (13.4%) locations respectively, when compared to the untreated control. Our study results suggest that these biopesticide treatment results were comparable in efficacy to the chemical seed treatment Gaucho®. Other two biopesticide products- Aza-Direct® and Pyganic 1.4® EC treatments did not provide effective control of P. cruciferae at both the locations.     

Infectivity of metalaxyl-sensitive and -resistant isolates ofPhytophthora infestans to whole potato tubers as affected by tuber aging and storage

Potato tubers (cv. Alpha) were harvested at various time intervals after planting, or removed from storage at various times after harvest, and inoculated with different sporangial concentrations of three metalaxyl-sensitive (MS) and three metalaxyl-resistant (MR) isolates ofPhytophthora infestans. Disease parameters recorded were: (a) percentage of infected tubers; (b) percentage of blighted tuber surface area; and (c) depth of lesions. Blight was negatively correlated with tuber age both in the field and in storage. Susceptibility of tubers declined with age in the field but increased temporarily in storage.MR isolates did not differ significantly from MS isolates in percent of infected tubers but produced significantly larger and deeper lesions in tubers. Whereas inoculum concentration had a significant effect on the percent of infected tubers and of infected tuber surface area, it did not affect significantly the depth of the lesions. The results indicate that the MR isolates tested are stronger tuber blighters than the MS isolates.     

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.     

Behavioral studies of the mobile forms ofsynclera univocalis on jujube,zizyphus mauritiana

One- or two-day-old larvae ofSynclera univocalis Wlk. (Pyralidae: Lepidoptera) were found mostly (83%) on young leaves of jujube (Zizyphus mauritiana Lamk. var.Umran) trees; in 67% of the cases the interveinal area of the tender leaves was folded. As the larvae grew older, the sides of the leaf were folded and the larvae fed within them. The leaf was turned inward by 71% of the larvae, while the rest turned the leaf outward. In 99% of the cases only one larva was found per leaf; very rarely were larvae of two different species of webbers found on the same leaf. The occurrence of the larvae was greatest at a tree height of 1.5-2 m. The distribution of the pest in the orchard was random. The percentage of adults on leaves was significantly higher than on webs, branches, the ground, or hovering. The maximum number of adults counted was at 13.00 hours.     

Neem kernel as an ovipositional repellent forSpodoptera litura (F.) moths

Laboratory and nursery tests showed that a 2% neem (Melia azadirachta L.) seed kernel suspension in water was effective as a repellent and ovipositional deterrent for moths of the tobacco caterpillar,Spodoptera litura (F.). The mean number of eggs laid on treated tobacco seedlings was 37 3 as against 1715 on control seedlings. As a consequence of the moths being repelled from the treated plants, they laid more eggs on the cloth and the glass surface in glass jar experiments. Repellency was even more pronounced when the moths were released in treated and untreated nylon-netting-caged nursery beds; the mean number of eggs laid on treated seedlings was then only 749 as against 19,713 in control beds.     

Suppression of powdery mildew in squash by applications of whitewash,clay and antitranspirant materials

The incidence of powdery mildew, caused bySphaerotheca fuliginea (Schlecht. Fr.) Polacci, in squash plants, was suppressed in the field to 50–60% of that in untreated control plants by weekly sprays with whitewash (Loven or Yalbin) or clay. Loven or Yalbin sprays resulted in significant reductions in disease level, more on the adaxial (59–65%) than on the abaxial (38–52%) surface of leaves, and more on young (53–59%) than on old (12–18%) leaves. The addition of 0.1% Dabak (a commercial sticker) to the whitewashes significantly increased their efficiency (22% above that of the controls), the degree of protection being associated with whitewash concentration. Squash leaves were protected from powdery mildew also by weekly sprays of the antitranspirant Vapor Gard, to a level comparable with that achieved by a whitewash plus sticker. However, the protection levels achieved with whitewashes, clays and antitranspirant were lower than with a fungicide (propiconazole). Experiments conducted under controlled conditions resulted in higher rates of escape from infection and a lower rate of hyphal and conidial development on plants and tissues following whitewash, clay and antitranspirant treatments.     

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.     

Suppression of Rhizoctonia solani in potato fields. 1. Occurrence

A search was made forRhizoctonia solani-suppressive soils by establishing many small experimental plots, half of which were planted withRhizoctonia-infected seed potatoes and the other half with disinfected seed stock. The sclerotium index of the harvested tubers was compared witht that of the seed potatoes. In suppressive soils, the sclerotium index of the harvest is much lower than that of the seed potatoes. None of the plots on holocene marine soils (loamy sand, sandy loam, clay loam and clay) proved to be suppressive in 1978 and 1979. Only on pleistocene, slightly acid sandy soil suppressiveness was observed. In 1978, four out of twelve plots showed suppressiveness when the plots were planted with seed potatoes produced on a sandy soil. In 1979, only two out of thirtyone plots were slightly suppressive when planted with seed potatoes produced on a young clay loam from a new polder. A higher percentage of sclerotia on tubers from sandy soils proved to be infected with antagonistic fungi (73%) than of those on tubers from marine clay or loam soils (25%). Factors that influence suppressiveness are suggested.     

Effects of fenamiphos and biocontrol agents on cotton growing in nematode-infested soil

Efficacy of a chemical nematicide, fenamiphos and three microorganisms in controllingRotylenchulus reniformis andTylenchorhynchus latus on cotton planted in field plots was investigated. Monthly records of the nematode population levels showed that fenamiphos had the highest (p0.05) levels of their control which resulted in the top cotton yield. Plots receiving the bacteriumBacillus sp. had various degrees of nematode control though their cotton yield was comparable (P0.05) to the fenamiphos-treated plots. Plots inoculated with a fungusChaetomium spirale recorded the least effect for controlling the two nematode species and their cotton yield was not significantly different from the untreated plots. Plots treated with an actinomycete,Streptomyces sp., had an intermediate effect on both nematode population densities and cotton yield. At harvest,T. latus population densities were equally suppresed (P0.05) in all treatments which should be reflected on the subsequent crop.With 2 tables     

Releases in israel ofAphelinus perpallidus,a recently introduced parasite of the pecan blackmargined aphid,Monellia caryella

Six shipments totaling 3452 mummies of the blackmargined aphid,Monellia caryella (Fitch), parasitized withAphelinus perpallidus Gahan, were obtained by air freight during the years 1982-1985 from Texas A&M Research Center, El Paso, Texas. About two-thirds of the mummies did not yield parasites. A colony ofA. perpallidus was established in the laboratory. Under laboratory conditions the percentage of emerged parasites was higher than that in the imported mummies, and the parasite had very limited impact on the aphid population. Field releases of the parasite were made but no establishment ofA. perpallidus was observed through the years.     

Effects of elicitors on trichothecene accumulation and <Emphasis Type="Italic">Tri</Emphasis> genes expression in potato tubers inoculated with <Emphasis Type="Italic">Fusarium sulphureum</Emphasis>

Postharvest losses due to pathogens are a major concern in agriculture and therefore new strategies to reduce these losses while making sure that the treated products are safe for the consumer, are of paramount importance. Chemical fungicides treatment is not only unsafe but also leads to pathogen developing resistance. Therefore, products that can reduce the development of dry rot of potato and mycotoxin accumulation, and be safe are needed. A better understanding of the induction of trichothecene biosynthesis is essential to reduce trichothecene production. The effects of three elicitors such as β-amino butyric acid (BABA), sodium silicate and chitosan, on the suppression of lesion development, trichothecene accumulation, and expression of Tri genes were assessed in potato tubers inoculated with Fusarium sulphureum. The results showed that lesion diameters were significantly reduced after treating with BABA at 100 mM for 3 d, sodium silicate at 100 mM for 2 d and chitosan at 0.50% for 3 d. Tri gene expressions were significantly down-regulated in inoculated tubers after elicitor treatments, and trichothecene accumulation were also suppressed. Meanwhile, the levels of trichothecene accumulation and Tri genes expression showed cumulative changes with the incubation time, extending after elicitor treatments. In addition, elicitor applications reduced more for type A trichothecene (T-2, DAS) than type B trichothecene (3ADON, Fus-X). It is possible that elicitors triggered downstream resistance genes to produce resistance related metabolites that suppressed the biomass of F. sulphureum, resulting in reduced Tri gene expressions and trichothecene accumulation.     

Integrative diagnosis and molecular phylogeny of dagger and needle nematodes of olives and grapevines in the island of Crete,Greece, with description of Xiphinema cretense n. sp. (Nematoda,Longidoridae)

The occurrence and geographic distribution of longidorid nematode species inhabiting the rhizosphere of cultivated and wild olive and grapevine in Crete Island were investigated. Morphological and morphometrical studies identified five Longidorus and six Xiphinema species, with frequencies of prevalence (for wild and cultivated olives and grapevines, respectively) as follows: Longidorus closelongatus (2.0–13.3 %), L. cretensis (1.0–6.7 %), L. moesicus (13.3 % only in grapevines), L. orientalis (3.3 % only in grapevines), L. pseudoelongatus (7.0 % only in olives), Xiphinema cretense n. sp. (3.0 % only in olives), X. index (3.0–23.3 %), X. israeliae (6.3 % only in olives), X. italiae (3.3–10.0 %), X. pachtaicum (26.7–42 %) and X. simile (3.3 % only in grapevines). Xiphinema cretense n. sp. is characterized by a body size 3,872–6,135 μm long, lip region anteriorly rounded, separated from the rest of the body by a depression, odontostyle and odontophore 140.6 and 80.3 μm long respectively, vulva position at 46.0–50.5 %, female tail 31.0–38.0 μm long, nearly hemispherical with curvature essentially dorsal and with a tip completely rounded or presenting a very short bulge, c ratio (119.1–186.9), c’ ratio (0.7–0.8). Molecular characterisation using D2-D3 expansion regions of 28S rRNA, 18S rRNA and ITS1-rRNA was carried out and maximum likelihood and Bayesian inference analysis were used to reconstruct phylogenetic relationships among these species and with other longidorids.     

Distribution and characteristics of the damage of the Syrian woodpecker,Dendrocopos syriacus (HEMP. & EHR.) (Aves: picidae), in polyethylene irrigation pipes in fruit orchards

The Syrian woodpecker,Dendrocopos syriacus (Hemp. & Ehr.), was found to attack black polyethylene pipes of both sprinkler and drip irrigation systems in Israel. Nut crops and deciduous fruits are preferred by the woodpecker, and trees infested by boring insects are favored. Damage to pipes is frequent in plots of avocado, citrus and grapevine bordered by rows of windbreakers, with the pipes near the windbreaker being the most severely attacked. In orchards without windbreakers the distribution of damage seems to be random, or concentrated near trees infected by boring insects, or near other attractive objects (e.g. electric poles).