Nontreated Control Treatments Research Articles

Novel use pattern of pendimethalin for annual ryegrass (Lolium rigidum Gaudin) control in wheat and barley

Annual ryegrass (Lolium rigidum Gaudin) is a problematic weed in most of the cropping regions in Australia. Evolved herbicide resistance to multiple modes of action groups, the lack of new herbicidal molecules, and the emergence of late cohorts in winter season crops necessitate the use of existing herbicides in an innovative way to control L. rigidum. Pendimethalin as pre-emergence (PRE) is used for L. rigidum control; however, it is unable to control late cohorts of L. rigidum in winter season crops. Pot studies were conducted from 2019 to 2021 to evaluate the effect of a post-emergence (POST) application of pendimethalin with six doses (0, 220, 440, 880, 1,760, and 3,520 g a.i. ha-1) on L. rigidum control in addition to crop safety in wheat, barley, and sorghum. POST application of pendimethalin was found to be safe for wheat and barley, and the biomass reduction in both crops at varied rates (220 to 3,520 g ha−1) of pendimethalin ranged from 10% to 20%. A dose–response study revealed that the pendimethalin dose required for 50% mortality and growth reduction of L. rigidum was 179 and 144 g ai ha−1, respectively. Pendimethalin at 880 g ai ha−1 completely killed late cohorts of L. rigidum. These results suggest that the POST application of pendimethalin can be used for the effective control of late cohorts of L. rigidum in wheat and barley crops. POST application of pendimethalin suppressed the biomass of sorghum plants compared with the non-treated control treatment, and biomass reduction in sorghum at different pendimethalin doses ranged from 32% to 40%. Results implied that POST applications of pendimethalin in wheat and barley can diversify herbicide programs in managing L. rigidum and may help in delaying the evolution of resistance in this weed.

High seeding rates, interrow mowing, and electrocution for weed management in organic no-till planted soybean

AbstractNo-till planting organic soybean [Glycine max (L.) Merr.] into roller-crimped cereal rye (Secale cereale L.) can have several advantages over traditional tillage-based organic production. However, suboptimal cereal rye growth in fields with large populations of weeds may result in reduced weed suppression, weed–crop competition, and soybean yield loss. Ecological weed management theory suggests that integrating multiple management practices that may be weakly effective on their own can collectively provide high levels of weed suppression. In 2021 and 2022, a field experiment was conducted in central New York to evaluate the performance of three weed management tactics implemented alone and in combination in organic no-till soybean planted into both cereal rye mulch and no mulch: (1) increasing crop seeding rate, (2) interrow mowing, and (3) weed electrocution. A nontreated control treatment that did not receive any weed management and a weed-free control treatment were also included. Cereal rye was absent from two of the five fields where the experiment was repeated; however, the presence of cereal rye did not differentially affect results, and thus data were pooled across fields. All treatments that included interrow mowing reduced weed biomass by at least 60% and increased soybean yield by 14% compared with the nontreated control. The use of a high seeding rate or weed electrocution, alone or in combination, did not improve weed suppression or soybean yield relative to the nontreated control. Soybean yield across all treatments was at least 22% lower than in the weed-free control plot. Future research should explore the effects of the tactics tested on weed population and community dynamics over an extended period. Indirect effects from interrow mowing and weed electrocution should also be studied, such as the potential for improved harvestability, decreased weed seed production and viability, and the impacts on soil organisms and agroecosystem biodiversity.

Seed germination biology of sweet acacia (Vachellia farnesiana) and response of its seedlings to herbicides

AbstractSweet acacia [Vachellia farnesiana (L.) Willd.] is a problematic thorny weed species in several parts of Australia. Knowledge of its seed biology could help to formulate weed management decisions for this and similar species. Experiments were conducted to determine the effect of hot water (scarification), alternating temperatures, light, salt stress, and water stress on seed germination of two populations of V. farnesiana and to evaluate the response of its young seedlings (the most sensitive developmental stage) to commonly available postemergence herbicides in Australia. Both populations responded similarly to all the environmental factors and herbicides; therefore, data were pooled over the populations. Seeds immersed in hot water at 90 C for 10 min provided the highest germination (88%), demonstrating physical dormancy in this species. Seeds germinated at a wide range of alternating day/night temperatures from 20/10 C (35%) to 35/25 C (90%), but no seeds germinated at 15/5 C. Germination was not affected by light, suggesting that seeds are nonphotoblastic and can germinate under a plant canopy or when buried in soil. Germination was not affected by sodium chloride (NaCl) concentrations up to 20 mM, and about 50% of seeds could germinate at 160 mM NaCl, suggesting high salt tolerance ability. Germination was only 13% at −0.2 MPa osmotic potential, and no seeds germinated at −0.4 MPa, suggesting that V. farnesiana seeds may remain ungerminated until moisture conditions have become conducive for germination. A number of postemergence herbicides, including 2,4-D + picloram, glufosinate, paraquat, and saflufenacil, provided >85% control of biomass of young seedlings compared with the non-treated control treatment. Knowledge gained from this study will help to predict the potential spread of V. farnesiana in other areas and help to integrate herbicide use with other management strategies.

English

Fungi in the genus Trichoderma are widely used as biological control agents because they can suppress plant pathogens and activate plant defense systems. In the present study, efficacy of microbial antagonists viz., T. harzianum and T. viride or their combination was evaluated against the pathogenic fungus Macrophomina phaseolina and their effect on enzymatic activities and phenol content of soybean [Glycine max (L.) Merr.] plants. Soybean seeds were inoculated with T. harzianum and T. viride separately or in combination, and sown in pots under green house and under field conditions. Host enzymatic activities and phenol levels were measured at 14, 28 and 42 days after sowing (DAS) in both field and greenhouse experiments. Seed treatments with T. harzianum, T. viride or their combination increased peroxidase, polyphenol oxidase and β-1, 3-glucanase activities, and also the total phenol content in soybean leaves as compared to a non-treated control treatment. Concentration of peroxidase and β-1, 3-glucanasepeaked at 14 DAS and decreased thereafter in all the treatments under greenhouse and field conditions. All the treatments showed the highest levels of total phenols and polyphenol-oxidase at 28 DAS under both greenhouse and field conditions. At 14 DAS in both trials, the combination of T. viride + T. harzianum resulted in the highest level of peroxidase and β-1, 3-glucanase activities. This combination also resulted in the highest levels of total phenols and polyphenol oxidase content at 28 DAS. Our findings demonstrated that application of Trichoderma species as seed treatment has potential to trigger key mechanisms of systemically acquired resistance in soybean, and thereby enhanced efficacy of disease management tactics. © 2021 Friends Science Publishers

Low intensity of high pressure processing increases extractable recovery of polyphenols and antioxidant activities of non-astringent persimmon fruit

This study aimed to investigate the effect of low intensity of high pressure processing (LHP) on bioactive compound content and the antioxidant capacity of persimmon before digestion and during simulated in vitro gastrointestinal digestion (IVD). The astringent and non-astringent persimmon cultivars treated with LHP at 100 MPa for 10 min were analyzed for polyphenols, antioxidant activities and bioaccessibility. The results showed that LHP treatment significantly increased (P < 0.05) the extractability of polyphenols and antioxidant activities of non-astringent persimmon by 1.5–2.0 folds as compared to the non-treated control treatment. Additionally, LHP exhibited positive results for non-astringent cultivar as indicated by the higher recovery of polyphenols (204–279%), bioaccessibility index (192–205%) and residual antioxidant activities (44–399%) in comparison to the control after IVD. However, LHP treatment did not affect astringent cultivar. These findings suggest that the LHP could be applied to enhance nutritional property of non-astringent persimmon and may be used for developing novel health products with high functional bioactive compounds which tolerate the digestion system.

EVALUATION OF TRICHODERMA HARZIANUM IN CONTROLLING LATE BLIGHT OF POTATO

Evaluation of Trichoderma harzianum in reducing mycelial growth of Phytophthora infestans as well as in controlling late blight of potato was done in Microbiology and Biocontrol laboratory and Net-house, Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh during 2019-2020, Bangladesh. The experiment was conducted using popular potato variety Diamant and native variety Challisha. T. harzianum was evaluated in net-house and in-vitro condition. Fungicide Indofil M-45 (Mancozeb) was used as positive check for comparison. In Net-house experiment, T. harzianum increased plant height, number of tubers and fresh weight of tubers over control treatment for the both of the varieties of potato. T. harzianum on late blight of potato (var. Diamant) showed a significantly better management over control treatment. In comparison to non-treated control treatment, reduced infection of late blight was found in the T.harzianum treated plants, whereas increase disease severity was calculated in control treatment. After harvesting, tuber infection in T. harzianum treated plants was not observed. Percent inhibition of tuber infection over control was 100%. Indofil M-45 suppressed Disease severity but comparatively less effective than T. harzianum in the long run. In case of variety Challisha similar trend of results were observed. In dual culture assay, T. harzianum showed highest inhibitory effect in suppressing mycelial growth of P. infestans. T. harzianum showed 86.67% inhibition of mycelial growth of P. infestans over control. Thus, it can be concluded that T. harzianum is effective to control late blight of potato and sometimes comparable to chemical fungicide in net-house condition.

In-Season Monitoring of Postharvest Rot Pathogens on European Pears (Pyrus communis) in Southern Oregon and Subsequent Management Strategies

Postharvest decay in pears is a disease complex caused by several fungal pathogens. To understand the presence of these pathogens on flower and fruit tissues at early stages of fruit development, we collected samples from two commercial pear orchards in southern Oregon at five stages of fruit development: cluster bud, full bloom, petal fall, fruitlets, and field bins during commercial harvest. We recovered four common postharvest decay pathogens, Alternaria spp., Botrytis cinerea, Cladosporium herbarum, and Penicillium expansum, which varied in frequency across these stages, suggesting that pathogens may initially infect flowers and fruitlets well before conventional preharvest fungicide sprays. In a separate experiment, we applied four fungicides early in the growing season and/or shortly before harvest to determine when treatment was most effective in reducing the recovery rate of these pathogens and reducing storage rot. The recovery of Alternaria spp., B. cinerea, and P. expansum from flowers and fruitlets was reduced by 33, 47, and 33%, respectively, with bloom-time fungicide applications compared with nontreated control treatments. In addition, the fungicide program that included bloom-time application, preharvest application, and postharvest application resulted in significantly lower storage rot incidence compared with preharvest and postharvest application only. Syllit (dodine) reduced the storage rot incidence by 71%, Inspire Super (difenoconazole + cyprodinil) by 52%, Nevado (iprodione) by 36%, and Merivon (fluxapyroxad + pyraclostrobin) by 33% compared with nontreated control treatments.

First Report of Ophiosphaerella agrostidis Infecting Creeping Bentgrass in Wisconsin

Dead spot is a disease of golf course putting greens and is caused by the pathogen Ophiosphaerella agrostidis Dernoeden et al. (syn. O. agrostis) (Câmara et al. 2000). The disease is found on creeping bentgrass (Agrostis stolonifera L.) and hybrid bermudagrass (Cynodon dactylon [L.] Pers. × C. transvaalensis Burtt-Davy) in the eastern and southern United States as well as Canada (Kaminski and Dernoeden 2002; Kaminski and Hsiang 2006; Krausz et al. 2001). In June 2017, disease symptoms resembling dead spot were observed on a golf course in Wisconsin. Small (<3 cm) necrotic spots first appeared approximately 10 months after establishment of a 50/50 blend of ‘007’ and ‘SR1119’ creeping bentgrass on sand-based putting greens. The disease became more severe during the summer months with as many as 10 spots per square foot and spots up to 4 cm in diameter. The disease was less severe on greens infected in 2017, but new symptoms appeared in 2018 on greens that were seeded during the summer of 2017. Dark brown ectotrophic hyphae were observed on bentgrass stolons, and pseudothecia were observed embedded within necrotic tissue. A single fungal morphotype was consistently isolated from leaves, stem bases, and stolons, and the colonies were rose-quartz color when cultured on potato dextrose agar. To demonstrate pathogenicity, ‘Penn A-1’ creeping bentgrass seedlings were grown for 4 to 6 weeks in 2.5-cm Cone-tainers in an autoclaved sand-based growing medium with a mechanical analysis of 95% sand, 4% silt, and 1% clay. Inoculum was prepared by placing mycelia from a hyphal-tipped isolate on an autoclaved mix of seed of tall fescue (Festuca arundinacea Schreb.) and wheat (Triticum aestivum L.) germ (50% [vol/vol]) and grown at 20°C for 10 days. The inoculum (5 g) was set at the surface of the sand and surrounding the stem bases of the creeping bentgrass in the center of each Cone-tainer (n = 6). A noninfested inoculum and noninoculated grass each served as a nontreated control. The grass plants grown in individual Cone-tainers were enclosed in clear plastic bags to increase relative humidity and incubated at 20°C under 14 h of light per day from fluorescent lights. Pathogenicity tests were conducted twice. No symptoms developed in either of the nontreated control treatments. After 7 days, tissue along the periphery of each inoculation point became covered by pink mycelia, and newly infected leaves appeared tan or brownish-red. Reisolation of the pathogen from symptomatic tissue produced fungal colonies similar in color, morphology, and growth rate to the original isolate. The internal transcribed spacer (ITS) regions of DNA from the original and reisolated fungus were amplified using ITS primer pair ITS1/ITS4. Sequencing of the amplified region resulted in a 408-bp sequence (GenBank accession no. MK561423) matching 100% identity with GenBank accession numbers AF191548.1 and MF351996.1. Based on field symptoms, morphological characteristics, pathogenicity tests, and ITS sequences, the pathogen was identified as O. agrostidis. To our knowledge, this is the first report of dead spot on creeping bentgrass in Wisconsin.

풋거름작물 재배 후 추비처리가 더덕의 생육 및 사포닌 함량에 미치는 영향

Background: This study was conducted to investigate the effects of fertilization with the application of mixed organic matter after cultivating green manure crops on the growth and saponin content of Codonopsis lanceolata Trautv.<BR> Methods and Results: Five type of cultivation of green manure crops were done: hairy vetch as a single seedling crop (HV), hairy vetch and rye as a mixture of seedling (HV/R), additional fertilization with mixed organic matter after cultivation of a seedling mixture (HV/R/MO), chemical fertilizer (CF), and a non-treated control (NT). The total nitrogen content was the highest in the HV/R/MO treatment, followed by the HV, CF, HV/R and NT treatments, respectively. Nitrogen fixation was higher in the single seedling treatment with hairy vetch (HV) than in the treatment with a mixture of hairy vetch and rye seedling (HV/R). Moreover, the growth of C. lanceolata was greatly increased by the application of additional fertilizer after treatment with the mixture of hairy vetch and rye seedlings. The HV/R/MO treatment produced the highest total lancemaside content among the treatments, followed by HV, HV/R, CF, and NT, respectively.<BR> Conclusions: It was verified that C. lanceolata experienced superior growth with the application of mixed organic matter as additional fertilizer after the cultivation of green manure crops, and the content of its major saponins, lancemasides were also increased by this treatment.

Cold Storage and Biocontrol Agents to Extend the Storage Period of ‘BRS Isis’ Seedless Table Grapes

‘BRS Isis’ is a novel hybrid seedless table grape with large reddish bunches. This cultivar is cultivated in tropical and subtropical areas and has potential to be exported overseas; however, under these growth conditions, grapes can be severely damaged by gray mold (Botrytis cinerea), the main postharvest disease of table grapes. Thus, this study aimed to evaluate different pre- and postharvest strategies to extend the storage period of ‘BRS Isis’ seedless table grapes. The treatments consisted of grapes packed into carton boxes under cold storage (1 °C and high relative humidity), pre- and/or postharvest treatment with potassium bicarbonate or a biological control agent (Bacillus subtilis), all with Botrytis inoculation. Additionally, two controls, with and without Botrytis inoculation, were also evaluated. The experimental design was completely randomized with eight treatments and three replications, and each plot consisted of four bunches. After a 50-day cold storage period, the carton boxes were kept for five days at room temperature (22 °C). Gray mold incidence and water loss, as well as soluble solids (SS), pH, titratable acidity (TA), SS/TA ratio, and color attributes were evaluated during both periods. Cold storage effectively reduced gray mold in ‘BRS Isis’ seedless grape for a period of 50 days, even when grapes were inoculated; however, no difference among treatments was observed. Higher water loss was observed in both non-treated control treatments.

Response of Japanese Privet to Plastic Mulch Applied over Nonspaced Containers

Mulches have many positive benefits for the production of plants, ranging from weed suppression to water conservation. In this study, a novel method of using plastic film mulch for container-grown plants was evaluated. Plots of 25 japanese privet (Ligustrum japonicum) in #1 (2.5 qt) nonspaced containers were wrapped with 1.25-mil white or black plastic mulch over the top and sides of containers. Small plants were planted through the plastic and grown for 22 weeks with overhead irrigation. Water application amount was determined by moisture sensors placed in the substrate of each treatment. Plant growth, dry weights (DWs), weed fresh weights, weeding time, substrate electrical conductivity (EC), substrate temperature, total water applied, and mulch costs were determined. Black plastic (BP) and white plastic (WP) mulch reduced water applied by 82% and 91%, respectively, compared with the nontreated control (NT). Nontreated control plants grew faster and had greater DW at the end of the experiment. Mulched containers had fewer weeds and required less labor to remove weeds than the NT treatment. Substrate EC level was greater in BP and WP treatments than for the NT after 20 weeks, and plastic mulch did not result in different substrate temperatures. Plastic mulch added $4.94/1000 containers ($2.24 input cost and $2.70 removal cost) to production costs, not including disposal costs. This novel method of mulching nonspaced plants reduced irrigation water, herbicide applications, and weeding labor, but probably added 2–3 weeks to finish time.

Mycelial growth inhibition of Rhizoctonia by indigenous medicinal plant extract

Pure cultures of four different isolates were established from the infected rice sheath collected different areas of Mymensingh District on the basis of different morphological characteristics including shape, colour (upper side and reverse side), sclerotial shape, sclerotial colour and compactness. The efficacy of six plant extracts viz. Garlic (Allium sativum), Neem (Azadirachta indica), Shetodron (Leucas aspera), Mahogoni leaf (Swietenia mahagoni), Mahogoni seed(Swietenia mahagoni) and Bishkatali (Polygonum hydropiper) was investigated against different the four isolates of Rhizoctonia sp. The radial mycelial growth of the fungus from 2-7 days was significantly differed among the different treatments. At 4 day after culture colony diameter was reached maximum (4.00 cm) in PDA plates of non-treated control treatment. Average colony diameter of Rhizoctonia sp. from 2-7 days after culture ranged from 0 cm to 4.00 cm. The highest colony diameter (4.00 cm) was recorded in control at 4 days after culture. At 4 days after culture, highest percent inhibition of radial mycelial growth over contril was found for Isolate 1 by Garlic (97.50%), Neem (96.75%), and Biskatali (94.25%); for Isolate 2 by Bishkatali (93.25%); for Isolate 3 by Bishkatali (95.75%), Mahogoni seed (85.75%) and Garlic (85.00%), and for Isolate 4 by Bishkatali (95.25%) and Shetodron (89.25%). Among the plant extracts, Bishkatali was highly effective to suppress mycelial growth of all isolates of Rhizoctonia sp.Progressive Agriculture 28 (3): 190-197, 2017

Effects of Insect Growth Regulators on Bagrada hilaris (Hemiptera: Pentatomidae).

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is a serious pest of cruciferous crops in the central coast of California. Management of B. hilaris primarily involves the use of broad spectrum insecticides, such as pyrethroids and neonicotinoids, when the pest invades a crop field. Insect growth regulators (IGRs) are known for their efficacy on nymphal stages of B. hilaris, but little is known about their transovarial effects. Thus, the major objective of this study was to determine the transovarial effects of IGRs such as novaluron, diflubenzuron, and azadirachtin, when adults are exposed to direct topical spraying and dried residues. In addition, a direct topical spray of IGRs on older instars (fourth and fifth instars) was examined at 1-, 3-, and 7-d post-treatment. The number of young instars (first and second instars) and adults was recorded up to ~31 d after exposure. In the topical spray assays, the number of young instars was significantly lower for novaluron, diflubenzuron, and azadirachtin than for the nontreated control. The number of young instars that emerged after novaluron treatment was low (0-11%). In the assays with dried residues, the number of young instars that developed was significantly lower for novaluron treatment than for the other IGRs and the nontreated control. There was no significant difference among diflubenzuron, azadirachtin, and nontreated control treatments in the development of young instars. In the assays with a topical spray of IGRs on older instars, significantly more nymphs died at 3 and 7 d after exposure. The IGRs had no clear impact on adults.

Soil and the foliage nutrient status following soil amendment applications in a Japanese cypress (Chamaecyparis obtusa Endlicher) plantation

ABSTRACTThe aim of this study was to evaluate the response of soil amendment applications on soil and the foliage nutrient status of a Japanese cypress (Chamaecyparis obtusa Endlicher) plantation established following clear-cutting in a pine-wilt-disease (PWD)-disturbed forest. We established four soil amendment treatments [(compound fertilizer (CF), compound fertilizer + biochar (CFB), compound fertilizer + sawdust (CFS) and a non-treated control treatment] in an 8-year-old Japanese cypress plantation. Soil organic carbon (C) and total nitrogen (N) were not significantly different (P > 0.05) between the soil amendment treatments and the control treatments, whereas extractable phosphorus (P), NH4+, K+, and Mg2+ concentrations were significantly affected by the addition of biochar in CF. The mean soil CO2 efflux rates during the study period were the highest in CFB (0.79 g CO2 m−2 h−1), followed by CFS (0.71 g CO2 m−2 h−1), CF (0.62 g CO2 m−2 h−1), and the control (0.46 g CO2 m−2 h−1) treatments. Foliar N and P concentrations were significantly higher in the CFB than in the control treatments. The results suggest that the addition of biochar in CF can enhance extractable soil nutrients and foliar N and P conditions of Japanese cypress established in a PWD-disturbed forest.

Management of laurel wilt of avocado, caused by Raffaelea lauricola

Laurel wilt is caused by Raffaelea lauricola, a nutritional symbiont of an Asian ambrosia beetle, Xyleborus glabratus. American members of the Lauraceae plant family are most susceptible and 300 million trees have been killed by the disease in the southeastern USA since 2003. Recently, commercial production of an important crop in the laurel family, avocado (Persea americana), has been affected in southern Florida. We summarize studies in which diverse measures were tested for managing the disease. In all studies, trees were treated with potential laurel wilt control measures and subsequently inoculated with R. lauricola. On potted plants in greenhouse experiments, commercial nutritional products (Greenstim and Keyplex 350) and SAR products (Agri-Fos and Nutri-Phite), when applied as soil drenches or foliar sprays, had either no impact on, or increased laurel wilt symptom development compared to non-treated control treatments. Bark applications of Tilt (a propiconazole fungicide for which emergency registration had been obtained in 2010) in a surfactant (Pentrabark) enabled significant laurel wilt protection in greenhouse studies on small potted plants, but Pentrabark and other surfactants moved little propiconazole into the xylem of fruit-bearing trees in field studies. In efficacy studies in the field, Propiconazole Pro (an injectable formulation of propiconazole), Tilt, and two experimental formulations of another triazole fungicide, tebuconazole, decreased the development of laurel wilt compared to nontreated control trees when applied as undiluted injections into branches and scaffold limbs (microinjection), or injection of dilute fungicide into tree flare roots (macroinfusion). However, symptoms developed in all treated trees by 10–11 months after inoculation with R. lauricola, indicating that trees would need to be re-treated at least on an annual basis. Regardless of how fungicides were applied, insignificant levels of different active ingredients entered fruit. Although fungicide treatment of fruit-bearing avocado trees is not a concern for food safety and several triazole and DMI fungicides can protect avocado trees from laurel wilt, cost-effective measures with which the xylem could be loaded with and protected by these products remains a challenge. Management of laurel wilt in commercial avocado production areas is discussed.

Pre-sowing Seed Treatments in Direct-seeded Early Rice: Consequences for Emergence, Seedling Growth and Associated Metabolic Events under Chilling Stress.

Double direct-seeding for double rice cropping is a simplified, labor saving, and efficient cropping system to improve multiple-crop index and total rice production in central China. However, poor crop establishment of direct-seeded early rice due to chilling stress is the main obstacle to wide spread of this system. A series of experiments were conducted to unravel the effects of pre-sowing seed treatments on emergence, seedling growth and associated metabolic events of direct-seeded early rice under chilling stress. Two seed priming treatments and two seed coating treatments were used in all the experiments. A non-treated control treatment was also maintained for comparison. In both the field and growth chamber studies, seed priming with selenium or salicylic acid significantly enhanced the emergence and seedling growth of rice compared with non-treated control. Nevertheless, such positive effects were not apparent for seed coating treatments. Better emergence and vigorous seedling growth of rice after seed priming was associated with enhanced α-amylase activity, higher soluble sugars contents, and greater respiration rate in primed rice seedlings under chilling stress. Taking together, these findings may provide new avenues for understanding and advancing priming-induced chilling tolerance in direct-seeded early rice in double rice cropping system.

Evaluation of Indaziflam for Greenhouse Use

Due to the relatively small market, volatility concerns, and high crop-value-per-acre associated with ornamental crops, no preemergence (PRE) herbicides are currently labeled for use in greenhouses containing plants. The objective of this study was to evaluate indaziflam SC for potential use as a PRE herbicide on gravel in greenhouses containing sensitive crops grown in extreme environmental conditions. Mini-greenhouses (MG) were designed and constructed to fit within gravel ground beds as an initial component to this study in order to evaluate herbicide volatility. Species evaluated included ‘Better Boy’ tomato (Lycopersicon esculentum Mill.), ‘Extreme Orange’ impatiens (Impatiens walleriana Hook. f.) and two species of petunia (Petunia × hybrida Juss. ‘Dreams White’ and ‘Dreams Neon Rose’). Indaziflam SC was applied at the manufacturer's labeled rate [40 g ai·ha−1 (0.04 lbs ai·A−1)] (1×) and at twice the labeled rate [80 g ai·ha−1 (0.07 lbs ai·A−1)] (2×). Each rate was applied using one of three different methods: 1) applied to only the gravel in ground beds with plants placed on gravel and covered with MG immediately following application; 2) applied over the top of plants on gravel inside the ground beds and covered with MG immediately application; and 3) applied over the top of plants outside the ground beds on adjacent gravel and left outside of MG. Two nontreated control treatments were maintained for each species and were placed either on nontreated gravel inside ground beds and covered with MG or placed outside ground beds on adjacent nontreated gravel and not covered with MG. Little to no injury was observed on any of the species after being placed on treated gravel and covered with a MG regardless of indaziflam rate. However when indaziflam was applied over-the-top, impatiens and tomatoes exhibited severe injury and death by 30 days after treatment (DAT). Additionally, fresh weights showed that all species receiving either over-the-top treatment were severely injured, while the plants placed on treated gravel inside the MG and both nontreated control treatments (both inside and outside of MG) exhibited no signs of injury or stunted growth. Results from this study indicate that while indaziflam may cause crop injury to ornamental species when applied over-the-top, it is likely that little to no injury will be observed as a result of volatility due to a gravel application in an enclosed structure.

Formulations of Bacillus subtilis BY-2 suppress Sclerotinia sclerotiorum on oilseed rape in the field

We are developing a collection of Bacillus strains, isolated from different environments, for use in controlling Sclerotinia sclerotiorum on oilseed rape in China and elsewhere. Strain BY-2, isolated from internal tissues of an oilseed rape root, was demonstrated to be Bacillus subtilis based on biochemical and morphological characteristics and on 16S RNA gene sequence. Photographic evidence from gnotobiotic studies using the lacZ-tagged strain BY-2(pUC18) confirmed that this strain was capable of colonizing internal root tissues. Strain BY-2 did not effectively colonize the ectorhizosphere or the surface of the stems or leaves of oilseed rape when applied in pellet or wrap seed treatment formulations. Populations of BY-2 dropped from 108 CFU seed−1 to 104 CFUg root−1 and ⩽102 CFUg stem−1 or leaf−1 after 60days. Strain BY-2 was applied as a pellet seed treatment formulation alone, as a spray at flowering alone, and as the pellet seed treatment formulation combined with the spray application in two field trials at the Wuxue location conducted in two consecutive years. These three treatments containing BY-2 provided disease control (disease incidence) and mean seed yield that was similar to the chemical control treatment and significantly greater than the pellet without bacteria and non-treated control treatments. All three of these BY-2 treatments were similar to each other with regard to these two metrics and to treatments containing B. subtilis Tu-100, a genetically distinct strain previously shown to be effective against this disease. In two additional field trials, conducted in consecutive years at the Wuhan location, strain BY-2 applied as a wrap seed treatment formulation alone, as a spray at flowering alone, and as the wrap seed treatment combined with the spray application provided disease control (disease incidence) and mean seed yield that was similar to the chemical control treatment. These three BY-2 treatments also were significantly greater than the non-treated control treatments and compared favorably to treatments containing Tu-100. There was no evidence of BY-2 promoting growth of oilseed rape when applied in the pellet or wrap seed treatment formulations in field trials conducted at the Wuxue or at the Wuhan locations. We now have three Bacillus strains (B. subtilis strains BY-2 and Tu-100, B. megaterium A6) that control S. sclerotiorum on oilseed rape in the field that can be tested in strain combinations for enhanced disease control. We also have multiple methods for application of Bacillus strains as both seed treatment and foliar applications were effective.

Use of Biocontrol Organisms and Compost Amendments for Improved Control of Soilborne Diseases and Increased Potato Production

Soilborne potato diseases are persistent problems in potato production and alternative management practices are needed. In this research, biocontrol agents (Bacillus subtilis GB03 and Rhizoctonia solani hypovirulent isolate Rhs1A1) and compost amendments (from different source material), were evaluated alone and in combination, for their potential to reduce soilborne diseases and increase tuber yield over three field seasons in Maine. Both biocontrol organisms reduced multiple soilborne diseases, stem and stolon canker by 20–38 %, black scurf by 30–58 %, and common scab by 10–34 % relative to the nontreated control treatment, and the combination treatment of both biocontrol organisms together provided nominally better control than individual treatments. However, biocontrol treatments had no direct effect on tuber yield. Compost amendments from different sources all increased total and marketable tuber yield substantially (11–37 % and 17–51 %, respectively) relative to nontreated controls. However, except for some reduction of Rhizoctonia canker, compost amendments did not reduce soilborne diseases (black scurf and commons scab) in any year, and resulted in increased levels of common scab in some years (20–45 % increase). The combination compost-biocontrol treatment, although did not perform significantly better than individual component treatments, still provided indications of combined beneficial effects from both component treatments. This research demonstrated the usefulness of these approaches and combinations as additional options for reduction of soilborne diseases and increased tuber yield and can be implemented for enhanced sustainability and productivity in potato production systems.

Response of a soil nematode community to liquid hog manure and its acidification

A study was conducted to determine why the number of opportunistic bacterial-feeding nematodes increase following addition of liquid hog manure and acidified mixtures of the manure to soil. A sandy loam soil harboring a wide range of nematode taxa, representing various trophic and colonizer–persister groups (c–p 1 through 5) and augmented with the plant-parasitic nematode, Pratylenchus spp., was used in microcosm experiments. Treatments were additions of liquid hog manure (0.15 v v −1 soil water), mixtures of manure (0.05, 0.10, and 0.15 v v −1 soil water) and sulfuric acid, as well as a sulfuric acid alone and a non-treated control. Three days post-treatment and during the presence of non-ionized volatile fatty acids from manure in soil, numbers of plant-parasitic nematodes, including Pratylenchus spp., decreased by at least 50% for all manure treatments compared to non-manure treatments. Thereafter, c–p 1 and c–p 2 nematode numbers increased in all manure but not in non-manure treatments. At week 4, c–p 1 and c–p 2 nematode numbers were greater by at least 6000 and 5000 individuals kg −1 soil, respectively, compared to non-manure treatments. In contrast, numbers of c–p 3–5 nematodes were not affected by the treatments. At week 4, the enrichment index, an assessment of the abundance of opportunistic c–p 1 and some c–p 2 nematodes compared to all c–p 2 nematodes, was around 70% for all manure treatments and lower, 32 and 29, respectively, for acid alone and non-treated control treatments. The increase in opportunistic nematodes following manure treatment was likely due to the increase in their food resources associated with the enrichment of the soil environment with readily degradable compounds. Volatile fatty acids present in the manure persisted in the soil for only four days before biological degradation. We conclude liquid hog manure is effective in killing plant-parasitic nematodes while increasing bottom-up food web interactions but not, as with soil fumigants, decimating top-down trophic interactions.