Induction of systemic protection against rust infection in broad bean by saccharin: effects on plant growth and development

Here, we examine the effect of saccharin on the induction of systemic resistance in broad bean (Vicia faba) to the rust fungus Uromyces viciae-fabae. Saccharin was applied to beans at the three-leaf stage, either as a soil drench or by painting the solution on to first leaves. Plants were then challenge inoculated with the rust 1, 6, 10 and 14 d following saccharin treatment, after which they were harvested, assessed for the intensity of rust infection and plant growth measurements conducted. Foliar application of saccharin did not induce systemic protection to rust infection until 14 d after application and was less effective than saccharin applied as a soil drench. When saccharin was applied as a drench, systemic protection was not observed until 6 d after application, but was still apparent in plants 14 d after application of the drench. Irrespective of the method of application, saccharin had no significant effect on fresh and dry weights or leaf area of the plants. Saccharin applied as a drench did, however, reduce the number of leaflets produced.     

Suppressing spread of Tomato spotted wilt virus by drenching infected source or healthy recipient plants with neonicotinoid insecticides to control thrips vectors

Field experiments were done to determine whether drenching plants with two systemically active neonicotinoid insecticides, thiamethoxam and imidacloprid, suppresses spread of Tomato spotted wilt virus (TSWV) by thrips vectors. Separate treatments to TSWV ‘infector’ tomato (source) and healthy lettuce (recipient) plants provided information on the relative importance of targeting control at virus acquisition by nymphs versus virus transmission to healthy plants by adults. Drenches were applied either to seedlings just before transplanting or to soil around plants. The thrips vectors recorded were Frankliniella occidentalis, F. schultzei and Thrips tabaci, but F. schultzei and T. tabaci predominated. Overall ratios of external to internal TSWV spread into and within plots without insecticide ranged from 1 : 2.3 to 1 : 2.8 between field experiments. Applying thiamethoxam as a soil drench to both young source plants and recipient seedling transplants suppressed TSWV incidence by 86%, while such application to either young source or recipient seedlings diminished incidence by 67–70%. When thiamethoxam was applied either as a soil drench to old source plants and concurrently as a seedling drench to recipient plants or as a seedling drench to recipient plants alone, incidence was suppressed by 65–73% and 54–73%, respectively. Thiamethoxam applied as a soil drench to old source plants diminished incidence by only 33% or not significantly. Imidacloprid applied either as a soil drench to old source plants and concurently as a seedling drench or as a seedling drench alone, suppressed TSWV incidence by 90–92% and 80% respectively. Although adult vector thrips and nymph numbers were low, fewer adults and/or nymphs were sometimes recorded due to insecticide application. Drenching healthy seedlings with neonicotinoid insecticides just before transplanting can be an effective chemical control measure to include in integrated disease management strategies to suppress TSWV epidemics in short‐duration crops like lettuce.     

Effect of Time of Application on the Action of Foliar Sprays of Oxamyl on Meloidogyne hapla in Tomato

Foliar sprays containing 3,000 or 4,000 ppm oxamyl applied before inoculation with Meloidogyne hapla completely protected tomato plants from intection for up to 36 days but sprays containing 1,000 or 2,000 ppm provided only partial protection. Postinoculation sprays were less effective than preinoculation sprays but they decreased the numbers of females and their rate of development and increased the numbers of males. Similar amounts of oxamyl applied to the soil as a drench or as granules controlled M. hapla more effectively than foliar sprays but the longer treatment was delayed after infection the fewer the larvae that were killed and the more that became male.     

Delivery methods for introducing endophytic bacteria into maize

The effectiveness of fivemethods for delivery of ten endophyticbacteria into maize stem and root tissues wasstudied in greenhouse conditions at EmbrapaMilho Sorgo, Sete Lagoas, MG, Brazil. Thedelivery methods included seed inoculation,soil drench, foliar spray, pruned-root dip andseed inoculation + soil drench. The bacterialendophytes were previously isolated from maizeplants, and reinoculated and recovered aftertreatments from maize, cv BR201. Each of thefive methods led to establishment and recoveryof bacterial endophytes in root tissues, butonly four isolates were recovered by the seedtreatment method. All 10 isolates wererecovered by pruned-root dip and seed treatment+ soil drench. No isolates were recovered instem tissues by the seed treatment method, andin the root by foliar spray method. However,all isolates were recovered in stem tissue bypruned-root dip method. The pruned-root dip wasthe most efficient method to deliver bacterialendophytes into maize. The isolate, BR201, wasrecovered by almost all methods in root andstem tissues. The results demonstrate thatendophytic bacteria can be recovered from maizetissues following inoculation by the differentmethods described, but the delivery depends onthe methods used and the endophytic bacterialisolate.     

Field tests of bacteria and soil-applied fungicides as control agents for take-all in winter wheat

Putative biological and chemical treatments for controlling take-all were used in each of three consecutive years at two locations where winter wheat crops were grown in naturally-infested fields. The chemical treatments more often decreased take-all than the biological treatments, but no treatment consistently and significantly decreased take-all, nor did any cause a significant increase in yield. An isolate of Bacillus cereus var. mycoides and one of B. pumilis, applied as soil drenches in autumn or spring, or in the seed furrows, were usually ineffective. Of the few significant effects on disease, half were associated with increases and half with decreases, and most occurred in April and did not persist to late June. Two strains of Pseudomonas pluorescens applied to the seed were ineffective. The fungicide benomyl, applied as a drench in autumn and spring at 20 kg/ha was ineffective, while nuarimol, applied as a drench in autumn at 2 kg/ha was sometimes effective. Nuarimol incorporated into the seed bed at 2 kg/ha was the most effective treatment. In analyses using a functional relationship model for data from treated and untreated plots 12% of 176 data sets for biological treatments, 38% of 96 data sets for chemical treatments and 81% of 16 data sets for combined treatments showed increasing efficiency of the treatment with increasing disease intensity. These findings also demonstrate an additional advantage of the experimental design, namely that treatments are tested at different disease intensity levels within fields.     

Application technique and irrigation method affect imidacloprid control of silverleaf whiteflies (Homoptera: Aleyrodidae) on poinsettias.

Subirrigation systems are increasingly used to water and fertilize greenhouse crops. They also appear to be well suited for the application of systemic pesticides. We conducted two studies to look at interactive effects ofimidacloprid application technique and irrigation method on plant uptake of imidacloprid and whitefly control. Drench applications of imidacloprid resulted in much higher concentrations in the leaves than applications to the bottom of pots after 14 d. However, imidacloprid efficacy in subirrigated plants was better if the imidacloprid was applied to the bottom of the pot than when an equal amount was applied as a drench. In drip-irrigated plants, imidacloprid efficacy was greater after a drench than after an application to the bottom of the pots. A second study showed that drench applications to drip-irrigated plants result in high imidacloprid concentrations in the bottom of the canopy, whereas bottom applications to subirrigated plants result in a more even distribution of imidacloprid throughout the plant. Surprisingly, the high leaf imidacloprid concentrations in the bottom layer of drip-irrigated plants did not result in improved whitefly control. Imidacloprid efficacy was better in subirrigated, bottom-treated plants than in drip-irrigated, drenched plants. Overall, results from these studies indicate that imidacloprid is very effective when applied to the bottom of subirrigated pots.     

内生拮抗细菌在哈密瓜植株体内的传导定殖和促生作用研究

采用抗生素标记的方法研究了内生拮抗细菌P38和B167菌株在哈密瓜植株体内的定殖动态和对植株生长的影响.结果表明,接种方法显著影响P38菌株在植株体内的定殖和传导,并以浸种处理最佳,蘸根和灌根处理次之,喷叶处理最差;浸种可使P38菌株在根、茎、叶中良好传导和稳定定殖,随着植株的生长,根内菌量呈下降趋势,而茎、叶内的含菌量先上升后下降;P38菌株还具有促进哈密瓜种子萌发和植株生长的作用.B167菌株只在根内定殖,在体内的扩展性较差,不能进入叶片;它对植株的生长表现出一定的抑制作用.     

Drench treatments for management of larval Japanese beetle (Coleoptera: Scarabaeidae) in field-grown balled and burlapped nursery plants

Insecticide drenches were applied to postharvest field-grown nursery plants harvested as 60-cm-diameter balled and burlapped (B&B) root balls for controlling third instars of Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae). Bifenthrin, chlorpyrifos, lambda-cyhalothrin, and thiamethoxam were drench-applied in fall and spring tests at volumes of runoff (1X; approximately equal 2.57 liters per drench per root ball) or twice runoff (2X). Tests also examined consecutive drenches (two, four, or six) and B&B rotation between drenches. Fall-applied drenches did not meet the Domestic Japanese Beetle Harmonization Plan (DJHP) standards of < or =1 grub and ranged from 0 to 90% control. However, most fall-applied drenches significantly reduced grub numbers relative to the untreated root balls. Spring-applied drenches were more effective than fall drenches: chlorpyrifos treatments gave 94-100% control, whereas other spring-applied treatments were less consistent, including thiamethoxam (83-100% control) and bifenthrin (61-100% control). Lambda-cyhalothrin was not effective. A higher drench volume (2X) did not significantly improve treatment efficacy; however, grub numbers decreased as the number of drenches increased for fall-applied chlorpyrifos and thiamethoxam and spring-applied bifenthrin. Rotation of root balls significantly reduced grub numbers compared with nonrotated treatments for fall-applied chlorpyrifos (six drenches) and bifenthrin (two or six drenches), but these treatments did not meet DJHP standards. The study indicates chlorpyrifos, bifenthrin, and thiamethoxam drenches can control Japanese beetle in the spring and may provide a new postharvest option to certify B&B plants for Japanese beetle.     

Effect of seaweed concentrate on growth and development of the marigoldTagetes patula

The seaweed concentrate Kelpak, made fromEcklonia maxima, and applied as a foliar spray or a root drench at transplanting, improved both the vegetative and reproductive growth of marigolds. Of particular significance is that the overall production of seeds (fruits) was increased by as much as 50% in some instances. Very low concentrations of seaweed concentrate were not always effective, while the higher dosages decreased vegetative growth.     

Induction of Local and Systemic Resistance to Colletotrichum coccodes in Pepper Plants by dl -β-Amino-n-Butyric Acid

dl -β-amino- n -butyric acid (BABA) that was applied as a foliar spray or soil drench to pepper plants induced local and systemic resistance to a challenge infection with Colletotrichum coccodes . About 85 and 100% protections against the anthracnose were achieved by a relatively high concentration of BABA at 1000 μg/ml, which had no antifungal activity in vitro against C. coccodes . Protection was expressed as a reduction in the number and size of lesions. dl -α-amino- n -butyric acid (AABA) was not so effective as BABA, whereas dl -γ-amino- n -butyric acid (GABA) provided a little protection against anthracnose. At least 5 days were needed after BABA treatment as a soil drench in order to induce resistance in pepper plants. After BABA treatment as a soil drench, the plants remained protected over 15 days. Application of BABA to the lower leaves significantly protected the leaves above the treated leaves from C. coccodes infection, which suggested that systemic resistance to the anthracnose was induced in pepper plants by BABA. The leaves above the BABA-treated lower leaves were strongly protected by reduction of the number and size of lesions.     

The modes of action of two benzimidazoles and thiophanate-methyl used for the control of Verticillium wilt of strawberry

Benomyl, thiabendazole and thiophanate-methyl were found to be fungistatic against Verticillium dahliae in vitro. All materials suppressed wilt symptoms on artificially inoculated strawberry plants when applied as a root dip, soil drench or a foliar application. Quantitative bioassays of the amount of toxic residues and fungal colonization in tissues of treated plants after root treatment revealed that these materials or their toxic breakdown products were readily translocated to crown and leaves: they suppressed the internal spread of the pathogen throughout the plant. After foliar application there was no marked basipetal movement of material within the plant: fungal colonization was greatly reduced in treated leaves, but the roots and crowns were colonized to a similar extent to those of untreated plants.     

Professional and consumer insecticides for management of adult Japanese beetle on hybrid tea rose

In many states, Japanese beetle, Popilliajaponica Newman (Coleoptera: Scarabeidae), is no longer quarantined, and management is left to professional applicators and consumers. Adult management in hybrid tea rose, Rosa L., was compared among biorational insecticides, novel imidacloprid applications (tablet, gel, and root dip), and conventional insecticides. Efficacy of biorational insecticides used by consumers varied widely and may not offer predictable management: mortality was 3.0% with Garlic Barrier, 5.0% with Monterey Neem Oil, 15.1% with Pygenic (1.4% pyrethrins), and 27.3% with Orange Guard (D-limonene). Only JB Killer (0.02% pyrethrins plus 0.2% piperonyl butoxide) had mortality of 90.9%, probably due to piperonyl butoxide. Professional biorationals did not show significant mortality: 7.7% with Azatin XL (azadirachtin) and 3.7% Conserve (spinosad). In contrast, conventional insecticides demonstrated significant mortality; 88.4% with Decathlon 20 WP (cyfluthrin) and 83.3% with Discus SC (imidacloprid plus cyfluthrin). New imidacloprid applications (tablet, gel, and root dip) worked as well as standard drench and granular methods, but they showed 9.1-42.7% mortality. However, beetles were incapacitated as demonstrated by inability to walk (82-106-s flip time) compared with controls (30-s flip time). No phytotoxicity was observed in any treatments. However, some imidacloprid treatments produced growth enhancement: higher leaf chlorophyll (1X, 3X granular, and one tablet), and larger leaf area and higher nitrogen (3X granular, drench). The highest (active ingredient) imidacloprid was in 3X granular treatment, which in an unplanned infestation, showed highest numbers of twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Effects of imidacloprid on leaf quality and mite outbreaks deserves research.     

Disinfection Alternatives for Control of Ditylenchus dipsaci in Garlic Seed Cloves

Hot-water dips with and without the additives abamectin and sodium hypochlorite were evaluated for control of Ditylenchus dipsaci infection of garlic seed cloves. All treatments were compared to hot water-formalin clove dip disinfection and to nontreated infected controls for garlic emergence, midseason infection, bulb damage, and yield at harvest in field plots in 12 experiments. Hot-water treatments without additives only partially controlled D. dipsaci when a warming presoak dip (38 C) of 30, 45, or 60 minutes'' duration was followed by a hot-water dip (49 C) of 15-30 minutes'' duration. Exposure to 49 C for 30 minutes caused slight retardation of garlic emergence, although normal stand was established. Abamectin at 10-20 ppm as the 20-minute hot dip (49 C) or as a 20-minute cool dip (18 C) following a 20-minute hot-water dip and sodium hypochlorite at 1.052-1.313% aqueous solution as the 20-minute hot dip were highly effective in controlling D. dipsaci and were noninjurious to garlic seed cloves. None of these treatments was as effective as a hot water-formalin dip and were noneradicative, but showed high efficacy on heavily infected seed cloves relative to nontreated controls. Abamectin was most effective as a cool dip. These abamectin cool-dip (following hot-water dip) and sodium hypochlorite hot-dip treatments can be considered as effective alternatives to replace formalin as a dip additive for control of clove-borne D. dipsaci. Sodium hypochlorite was less effective as the cool dip, and at concentrations of 1.75-2.63% was phytotoxic to garlic.     

Effect of seaweed concentrate on the establishment and yield of greenhouse tomato plants

Seaweed concentrate prepared fromEcklonia maxima (Osbeck) Papenfuss, when applied as a soil drench, significantly improved the growth of tomato seedlings. Application as a foliar spray had no effect on young plants. In a second experiment SWC-treated plants exhibited early fruit ripening and a total fruit fresh weight increase of 17%. The number of harvested fruit were improved by about 10%. In this instance foliar applied SWC was more beneficial than SWC applied to the soil. The significance of these findings is discussed.author for correspondence     

Some effects of differently-acting nematicides on the cereal cyst-nematode (Heterodera avenae) and on the appearance of ''scorch'' in spring wheat on light loamy sand

In fungitoxicity tests against Phytophthora cinnamomi on Chamaecyparis lawsoniana cv. Ellwoodii, a drench of furalaxyl (1000 mg a.i./l) applied to the compost in which 1-yr-old plants were growing, 1 wk before they were inoculated with 650 000 zoospores, controlled disease for at least 12 months. With an inoculum dose of 650 zoospores/plant, furalaxyl at 500 mg a.i./l controlled disease even when inoculation was 12 wk after fungicide treatment. Aluminium tris (ethyl phosphonate) (2000 mg a.i./l) applied as a drench 1 wk before inoculation with 650 000 zoospores/plant did not prevent root infection but delayed foliar symptoms for 9 months: the same treatment, using etridiazole (500 mg a.i./l) only slightly reduced disease incidence. When applied as a single drench 2 days before inoculation, prothiocarb (2000 mg a.i./l) and cuprammonium compounds (200 mg a.i./l) were much less effective than furalaxyl (1200 mg a.i./l), sodium ethyl phosphonate (1500 mg a.i./l), aluminium tris (ethyl phosphonate) (1500 mg a.i./l) or etridiazole (500 mg a.i./l). However, a drench of furalaxyl at 1000 mg a.i./l, aluminium tris (ethyl phosphonate) at 2000 mg a.i./l or etridiazole at 500 mg'a.i./l did not eradicate P. cinnamomi from compost containing infected root debris. Pre-planting drenching of the compost was ineffective. All fungicide treatments were non-phototoxic to 1-yr-old C. lawsoniana cv. Ellwoodii. These results are of special relevance to the control of P. cinnamomi on container-grown woody ornamentals.     

Prospects for fungicidal control of take-all of wheat

A range of fungicides and herbicides was tested against Gaeumannomyces graminis (causal agent of take-all) on agar plates, and on wheat seedlings in pots and in liquid culture. Benomyl, the standard in all tests, was consistently most effective: like iprodione, nuarimol and KWG 0599 , it diminished infection from inoculum placed just below the seeds more effectively when applied as a drench than as a soil-mix. Benomyl as a soil-mix was most effective in soils with least organic matter. Some compounds toxic to the pathogen on agar plates and in plants grown in liquid culture were ineffective as soil treatments. The practical limitations of soil treatment with conventional fungicides and application methods are discussed.     

Evaluation of insecticides and application methods against Contarinia nasturtii (Diptera: Cecidomyiidae), a new invasive insect pest in the United States

The midge Contarinia nasturtii (Keiffer), a serious gall-forming insect pest of cruciferous plants in Europe and southwestern Asia, was first reported in the United States in summer 2004. It had not been recorded in North America until its discovery in Ontario, Canada, in 2000. Efficacy of 20 insecticides belonging to 12 different classes was evaluated by using a foliar spray, soil drench, or seed treatment method. The broccoli cultivar 'Packman' was used in all tests at the suitable stage of four to five true leaves. Results indicated that foliar sprays of lambda-cyhalothrin, acephate, acetamiprid, chlorpyrifos, and methomyl reduced C. nasturtii larval populations by 96.7-100%. Except for acetamiprid, the other four insecticides also were effective against adults and provided 100% mortality after 24 h. When applied by drench, acetamiprid, imidacloprid, and thiamethoxam provided 100% control of C. nasturtii larvae, and the duration of efficacy lasted at least 7 wk. When applied as seed treatment, clothianidin and thiamethoxam provided 100% control of larvae and did not significantly affect seed germination. Imidacloprid also provided 100% control but the percentage of germination after treatment was only 62% (96.9% in check). These results indicate that several insecticides may significantly reduce midge populations. The nicotinoid class of insecticides, which has strong systemic activity, is likely to be the first choice. It is necessary to explore and develop other control methods such as cultural control and host resistance to develop an effective integrated pest management system.     

A novel method for the quantitative assessment of the percolation of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> conidia through horticultural growing media

Incorporation of fungal biological control agents (BCAs) into plant growing media has considerable ergonomic and economic benefits for growers. These agents usually give prophylactic control of target pests and diseases. However, their efficacy is dose dependent and loss of inoculum through leaching could influence the degree of protection they provide. At present there are no protocols to determine the loss of inoculum in the disparate growing media used in horticulture. We describe a method based on a nutrient leaching column to quantify leaching of conidia of the insect-pathogenic fungus Metarhizium anisopliae in a range of growing media. Conidia of this biocontrol agent were applied as a drench or premixed into the medium. Both the application method and growth medium influenced conidial leaching. Inoculum losses were greater following drench application than premixing (95% vs. 15%) irrespective of media type. Comparatively more inoculum was lost from bark and coir following drench application whereas losses were relatively high in peat following premixed application. The leaching column assay provided a simple and accurate method to quantify inoculum loss in real time. This assay could help determine leaching of other fungal BCAs in growing media. It could help in improving pest and disease control by optimizing the rate and frequency of conidial application as well in the design of more efficacious formulations.     

Caffeine as a novel toxicant for slugs and snails

In this study, caffeine is shown to act as both a repellent and toxicant against slugs and snails. This research is the first to document the potential of caffeine as a molluscicide. A drench treatment using a 1% or 2% solution of caffeine caused 100% of slugs (Veronicella cubensis) to exit treated soil, and the majority of these slugs subsequently died from caffeine poisoning. A 2% solution of caffeine applied to the growing medium of orchids killed 95% of orchid snails, (Zonitoides arboreus), and gave better control than a liquid metaldehyde product representing the standard commercial control for this pest. Using leaf‐dip bioassays, we discovered that slugs tended to avoid feeding on plant material treated with caffeine solutions 0.1%, and caffeine solutions as low as 0.01% significantly reduced overall feeding by slugs. Due to concerns about chemical residues, available molluscicides generally cannot be applied directly to food crops for control of slug and snail pests. Caffeine is a natural product which is approved as a food additive. Therefore, caffeine may prove useful for protecting food crops from slugs and snails.     

Specificity and mode of action of BTS 44584 and chlormequat chloride on wheat and soybeans

The selective action of the growth retardants chlormequat chloride and BTS 44584 on the growth of wheat and soybean was investigated. Chlormequat chloride retarded the growth of wheat whether applied as a seed soak, foliar spray or soil drench, at concentrations from 10^-2 M to 10^-4 M, although effectiveness depended on the age of the plant at application. BTS 44584 retarded the growth of wheat only when applied to the seeds. In soybeans, chlormequat chloride did not retard elongation growth when applied as a seed soak but showed some effects when applied as a foliar spray and more especially as a soil drench. Irrespective of the type of application, treatment with BTS 44584 retarded growth of soybeans. Thus, the selective action of the two compounds was not solely related to different species but also to timing and mode of application.