Effect of Phosphorus and Arbuscular Mycorrhizal Fungi (AMF) Inoculation on Growth and Productivity of Maize (Zea mays L.) in a Tropical Ferralsol

Soil fertility in the Lubumbashi region often proves to be limiting factor for crop production due to their low nutrient reserves. The objective of this work was to evaluate the impact of arbuscular mycorrhizae on phosphorus uptake by maize on Ferralsol. The trial was conducted in pots with 30?kg or 60?kg of P₂O₅ ha^?1 and a control. These three levels of phosphorus were combined or not with arbuscular mycorrhizae. The combinations of 30?kg or 60?kg of phosphorus with the inoculum led to a male flowering of maize at 63 days after semi. Maize treated with 60?kg of phosphorus ha^?1 formed very few or almost no blisters in the roots. Cob weight, length, diameter, number of rows and kernel weight varied significantly with phosphorus on both inoculated and uninoculated pots. The inoculated plants had high averages for these yield parameters. Due to the lack of phosphate fertilizer, inoculum alone can be an alternative to phosphorus provided that nitrogen and potassium are added, resulting in small but seed-filled ears compared to the phosphorus-free control without mycorrhizae, which resulted in empty ears. Yield varied significantly with the addition of phosphorus (0.3 to 6.1 tons ha^?1) and less significantly with inoculum (3 to 3.7?t ha^?1). The combination of treatments showed a significant difference in favour of the 60?kg of phosphorus or 60?kg of phosphorus associated with the inoculum. The highest phosphorus content was obtained on the inoculum treatment alone, which provided 1.4?mg phosphorus?g^?1 maize compared to other treatments, which provided 0.69 to 0.71?mg phosphorus?g^?1 maize.

     

Impact of Irrigation Timing and Weed Management Practices on Chlorophyll Content and Morphological Traits of Tomato (Solanum lycopersicum Mill.)

Weeds are a major biotic constraint; compete with crop for the same resources and ultimately reduce productivity. This study evaluated the impact of irrigation intervals and weed management treatments on chlorophyll content and morphological growth of tomato to find an appropriate integrated weed management strategy. Two-year field experiments (2018/2019) were conducted at district Mardan (34°15′38″ N and 72°6′36″ E). Tomato F1 hybrid (Taj?3592) was transplanted during March. The experiments were laid out in a randomized complete-block design in split-plot arrangement with three replications. The main block comprised three irrigation intervals (3, 6, and 9 days) and the sub-block included weed management treatments: transparent polythene, black polythene, weeding except Orobanche, sole weeding of Orobanche, weeding of all weeds, copper oxychloride 1.5?kg a.i ha^?1 (single dose), copper oxychloride 1.5?kg a.i ha^?1 (split doses), copper oxychloride?+?humic acid 25?kg ha^?1 (single dose), copper oxychloride?+?humic acid 25?kg ha^?1 (split doses), copper sulphate 2?kg ha^?1 (single dose), copper sulphate 2?kg ha^?1 (split doses), ammonium sulphate 200?kg ha^?1 (single dose), ammonium sulphate 200?kg ha^?1 (split doses), pendimethalin 33 EC 1.44?kg a.i ha^?1, glyphosate 48 SL 1.5?kg a.i ha^?1, and weedy check. Lowest relative weed density (RWD) of O. cernua (2.23%) and highest RWD of O. cernua (38.01%) were recorded in the 3? and 9?day irrigation intervals, respectively. However, 3?day irrigation interval resulted in highest fresh weed biomass (5794?kg ha^?1). Moreover, the 6?day irrigation interval significantly increased chlorophyll content by 11 and 5%, leaf area by 23 and 6%, and number of branches plant^?1 by 30 and 22% compared to 9? and 3?day irrigation intervals, respectively. Among the weed management treatments, black polythene resulted in the highest weed control efficiency (96%), increasing chlorophyll content by 16%, leaf area by 33%, and number of branches plant^?1 by 64% vs. weedy check. Consequently, 6?day irrigation intervals?×?black polythene could be the best weed management strategy, followed by transparent polythene, weeding of all weeds, pendimethalin, glyphosate, and ammonium sulphate.

     

Effect of riboflavin on postharvest disease of Asia pear and the possible mechanisms involved

The effects of riboflavin (vitamin B₂) against Alternaria rot caused by Alternaria alternata and its possible mechanism in harvested Zaosu pear fruit were investigated. Riboflavin at a concentration of 1.0?mM effectively inhibited development of Alternaria rot and enhanced the activities of defense-related enzymes, such as phenylalanine ammonia-lyase (PAL), polyphenoloxidase (PPO) and peroxidase (POD), and increased accumulation of flavonoids, phenolics and lignin. Riboflavin also affected reactive oxygen metabolism of pear fruit by increasing O ₂ ^?C production and H₂O₂ content, and enhancing the activities of the main detoxifying enzymes, such as catalase (CAT) and superoxide dismutase (SOD). Spore germination and mycelial growth of A. alternata were inhibited by riboflavin and the inhibitory effect was highly correlated with the riboflavin concentration used in this study. It is suggested that the effects of riboflavin on Alternaria rot in pear fruit may be associated with its direct fungitoxic property against the pathogens, and the elicitation of biochemical defense responses in the fruit.     

Interference between triazine-resistant Brassica napus and Panicum miliaceum

Atrazine carryover often limits growers to production of atrazine-tolerant crops the year following application, and allows the increase of triazine-tolerant weed species such as Panicum miliaceum L. (wild proso millet). Tiriazine-resistant Brassica napus L. cv. ‘Triton’ (oilseed rape) was tested to characterize the nature of interspecific interference with P. miliaceum. In a greenhouse study, atrazine at 2.2 kg ha^?1 depressed oilseed rape fruit (siliqua) number and fruit dry weight, and delayed flowering, but did not significantly affect height or weight of shoots, Oilseed rape fruit weight was reduced at 200 P. miliaceum plants m^?2. fruit number and shoot weight were inhibited at 400 weeds m^?2. and height was reduced and flowering delayed at 600 weeds m^?2. Number and weight of fruits were reduced by one-third after 8 weeks of interference as compared to oilseed rape grown with the weed for 4 weeks. Oilseed rape height was reduced by 29% and shoot weight by 55% by 600 weeds m^?2 and 2–2 kg ha^?1 atrazine, while fruit number and weight were reduced by 72%. Oilseed rape shoot weight was reduced by 74% by 600 weeds m^?2 for 12 weeks of interference, while fruit number and weight were reduced by 85% and 82%. respectively. In a field study, fluazifop reduced early season P. miliaceum cover by 72%, but did not increase oilseed rape cover. Mid-season P. miliaceum shoot weight was decreased by 97% by fluazifop and oilseed rape shoot weight was increased by 34%. P. miliaceum control increased oilseed rape biomass by 38% at 89 days, but biomass of oilseed rape sown at 11.2 kg ha^?1 with 2.2 kg atrazine ha^?1 was not decreased by P. miliaceum interference at 89 days.     

Evaluation of Water and Nitrogen Use Efficiency,Digestibility and Some Quantitative and Qualitative Characteristics of Forage Beet Cultivars Under Different Irrigation Methods and Nitrogen Levels

The aim of this study was to evaluate the water and nitrogen use efficiency and some quantitative and qualitative characteristics of forage beet cultivars under the influence of different irrigation methods and nitrogen levels in two cropping years, 2017–18 and 2018–19, at Agricultural Research Station in Karaj, Iran. Experimental factors included the first factor with four irrigation methods (normal leakage, alternate furrow irrigation, fixed furrow irrigation, type (drip-strip)), the second factor was the amount of nitrogen fertilizer with three levels (150, 200 and 250?kg N ha^?1) and the third factor included three forage beet cultivars (Sbsi052, Jamon and Kyros). Among irrigation treatments, alternate furrow irrigation and fixed furrow irrigation had the highest sugar content with 9.28% and 9.17%, respectively. The highest yield of digestible organic matter was obtained in leakage irrigation treatment, nitrogen fertilizer of 250?kg ha^?1 and in Kyros at the rate of 19.45?t ha^?1. The highest yield of root digestible dry matter, potassium, sodium and free nitrogen was observed in leakage irrigation treatment and consumption of 200?kg ha^?1 nitrogen was observed in foreign cultivars. The highest crude protein was observed in alternate furrow irrigation conditions with a consumption of 200?kg ha^?1 nitrogen in cultivar Sbsi052 at 13.08%. Leakage irrigation and type tape had the highest consumption efficiency and efficiency of nitrogen uptake with application of 150 and 200?kg ha^?1 N, and the highest water use efficiency was also observed in leakage irrigation and type tape with application of 250?kg ha^?1 N in domestic and foreign cultivars. The type irrigation method showed better quantitative and qualitative yield than the furrow irrigation methods.

     

Response of Cape gooseberry (Physalis peruviana L.) to nitrogen application under sandy soil conditions

The effect of different nitrogen (N) levels on growth and productivity of Cape gooseberry, cultivated in new reclaimed lands (sandy soil) at Nubaria region in Egypt, was investigated. Nitrogen levels were applied at rates of 50, 100, 150 and 200?kg?N?ha^?1 as ammonium sulfate. The amount of??N for each treatment was divided into five applications (after transplanting, seven days later, at the beginning of flowering, during fruit set and after the first harvest). Several growth parameters and yield were recorded in addition to nitrogen content in leaves. The results revealed that Cape gooseberry plants responded positively to nitrogen levels in sandy soils. Yield, number of fruits, and diameter of fruits increased significantly by increasing the nitrogen level up to 200?kg?N?ha^?1. Moreover, plant height, number of leaves, N-content in leaves and N-uptake shows a positive reaction to increased nitrogen supply. The quantitative effects of nitrogen on Cape gooseberry plants and the possible explanations of plant responses are discussed.     

Effects of tillage on winter wheat production in Mediterranean dryland fields

The benefits of conservation agriculture (CA) and associated technologies are not equal for all agro ecosystems. This study used a field experiment to examine winter-wheat yield and weeds under conservational and conventional systems in the central region of Spain. The three tillage treatments were conventional tillage (CT), minimum tillage (MT) and no-tillage (NT). The climatic conditions influenced wheat yield, yield components, soil water content and weeds. When the autumn-winter rainfall was abundant and constant (69.7% of annual rainfall), wheat grain yield (4465?kg?ha^?1) and yield components (3897?kg?ha^?1 of straw biomass and 584.5 ear m^?2) were highest. Wheat grain yield was highest with NT: 3549.9?kg?ha^?1 (compared to MT: 2955.1?kg?ha^?1 and CT: 2950.3?kg?ha^?1) and ear number per m² was significantly lower with MT (332 no ear m^?2, compared to 426 and 411.6?ear?m^?2 in CT and NT-systems respectively). Soil water content, at earing stage, was the highest in NT (27.36% of soil moisture) while MT showed the lowest content (11.83% of soil moisture). The higher weed measurements (means of 2.557 plants m^?2; 1.443 species m^?2 and 2.536 g m^?2) was with higher annual rainfall (488?mm). Throughout the experiment it was the dominant presence, in MT-wheat plots, of Lolium rigidum Gaudin (with means from 4.87 to 7.71 plants m^?2), which reduced the ear number per m². Our study revealed that in the short term, under semi-arid conditions, only the adoption of NT system (rather than MT) showed economic benefits.     

Ascorbic Acid Enhances Growth and Yield of Sweet Peppers (Capsicum annum) by Mitigating Salinity Stress

Salinity is a crucial problem which has affected crop productivity globally. Ascorbic acid is considered helpful against abiotic stresses due to its powerful antioxidant potential. In the pot experiment, salinity stress (0, 35, 70, and 105?mM) was applied to sweet peppers in split doses after 20 days of transplantation. To mitigate the adverse effects of salinity, ascorbic acid (0, 0.40, 0.80, and 1.20?mM) was applied as foliar spray after a 6-day interval during vegetative growth. Sweet pepper plants sprayed with distilled water (control) recorded maximum plant height (cm), leaf area (cm²), number of branches, stem diameter (mm), number of fruit plant^?1, fruit diameter (cm), yield plant^?1 (g), and chlorophyll content (mg 100?g^?1), while the maximum polyphenol oxidase (PPO) activity (unit mg protein^?1 min^?1) and ascorbate peroxidase (APX) activity (unit mg protein^?1 min^?1) were recorded in plants treated with 70?mM NaCl application. Salinity stress beyond 70?mM significantly reduced all the studied parameters. An ascorbic acid concentration of 1.20?mM significantly mitigated the negative effects of salt stress and recorded maximum plant height (cm), number of leaves plant^?1, leaf area (cm²), number of branches plant^?1, stem diameter (mm), number of fruit plant^?1, fruit diameter (cm), yield plant^?1 (g), chlorophyll content (mg 100?g^?1), PPO activity (unit mg protein^?1 min^?1), and APX activity (unit mg protein^?1 min^?1). Hence, a 1.20?mM concentration of foliar ascorbic acid could be used in saline conditions up to 70?mM of sodium chloride (NaCl) for better growth, productivity, and enzymatic activity of sweet peppers.

     

Residues in blackcurrants,fodder peas,spinach and potatoes treated with sublethal doses of 2,4,5-T to simulate wind drift damage

Blackcurrants, treated with 0.1 kg of 2,4,5-T ha^?1 (as esters of mixed C₄–C₆ alcohols; ‘Tormona 80’), contained 0.1 mg of 2,4,5-T residues kg^?1 in the berries at ripeness 29 days after treatment. Total residues in the berries were not reduced during growth and ripening, although the residue concentrations declined in the same period due to growth dilution. In spinach leaves from old plants, treated with 0.1 kg ha^?1, 0.05 mg of 2,4,5-T kg^?1 was found 14 days after treatment. Fodder peas showed no residues (< 0.002 mg kg^?1) at harvest 62 days after treatment with 2,4,5-T esters. After application of 0.1 kg ha^?1 on potato plants, the disappearance of 2,4,5-T was rapid during the first month, but residues were translocated into the tubers and reached a constant level of 0.02 mg kg^?1 after 1 month until harvest at 108 days after treatment. In all crops, visible effects were observed after treatment with 0.1 kg ha^?1. After the application at 0.01 kg ha^?1, phytotoxic effects were observed only in blackcurrants, but negligible residues were found in all the test crops.     

Target-site mutation associated with glufosinate resistance in Italian ryegrass (Lolium perenne L. ssp. multiflorum)

BACKGROUND: Studies were conducted to elucidate the mechanism of glufosinate resistance in an Italian ryegrass population. RESULTS: Glufosinate rates required to reduce growth by 50% (GR₅₀) were 0.15 and 0.18 kg AI ha^?1 for two susceptible populations C1 and C2 respectively, and 0.45 kg AI ha^?1 for the resistant population MG, resulting in a resistance index of 2.8. Ammonia accumulation after glufosinate treatment was on average 1.5 times less for the resistant population than for the susceptible populations. The glufosinate concentrations (µM ) required to reduce the glutamine synthetase (GS) enzyme activity by 50% (I₅₀) were 31 and 137 for C1 and C2 respectively, and 2432 for the resistant population MG. One amino acid substitution in the plastidic GS2 gene, aspartic acid for asparagine at position 171, was identified in the resistant population. CONCLUSIONS: This is the first report of glufosinate resistance in a weed species that involves an altered target site. Copyright © 2012 Society of Chemical Industry     

Effect of the new pyrazole carboxamide fungicide penthiopyrad on late leaf spot and stem rot of peanut

BACKGROUND: Management of early leaf spot (Cercospora arachidicola Hori.), late leaf spot [Cercosporidium personatum (Berk. & MA Curtis) Deighton] and stem rot (Sclerotium rolfsii Sacc.) of peanut (Arachis hypogaea L.) in the southeastern USA is heavily dependent upon sterol biosynthesis inhibitor (SBI) and quinone outside inhibitor (QoI) fungicides. Effective new fungicides with different modes of action could improve overall disease control and extend the utility of the current fungicides. Penthiopryad is a pyrazole carboxamide fungicide being evaluated for use on peanut. Field experiments were conducted from 2004 to 2007 to determine the effect of a range of rates (0–0.36 kg AI ha^?1) of penthiopyrad on leaf spot and stem rot and the relative efficacy of penthiopyrad and current fungicide standards chlorothalonil, tebuconazole and azoxystrobin. RESULTS: Leaf spot control in plots treated with penthiopyrad at 0.20 kg AI ha^?1 or higher was similar to or better than that for the chlorothalonil standard. The incidence of stem rot for all penthiopyrad treatments was usually less than that for the tebuconazole or azoxystrobin standard treatments. Pod yields for all penthiopyrad treatments were similar to or higher than those for the respective standards. CONCLUSION: Penthiopyrad has excellent potential for management of late leaf spot and stem rot of peanut, and may complement current SBI and QoI fungicides. Copyright © 2008 Society of Chemical Industry     

Nutrient uptake and yield of tomato under various methods of fertilizer application and levels of fertigation in arid lands

With rising concern about current irrigation and fertilizer NPK management, the present study was conducted to evaluate the effect of sources and methods of fertilizer application on nutrient distribution, uptake, recovery and fruit yield of tomato grown in a sandy soil. Equal amounts of NPK were applied in solid form or through fertigation at levels of 0%, 50%, 75% and 100% with the remainder 100%, 50% and 25% applied as solid fertilizers to the soil. Available NO₃ ^?-N and K were confined to the root zone of tomato in 75% and 100% NPK fertigation levels, while they moved beyond the root zone when they applied in two equal splits as solid fertilizers with drip (0% fertigation) and furrow irrigation. The mobility of P was greater in the root zone following its application through fertigation compared to a solid application as super phosphate. Drip irrigation showed significantly higher absolute growth rate (AGR), total dry weight (TDW) and leaf area index (LAI) of tomato over furrow irrigation. Moreover, tomato plants were able to utilize applied nutrients more efficiently in fertigation system than with conventional solid fertilizer application. Highest AGR, TDW and LAI were recorded when nutrients were applied to 100% by drip fertigation. The fruit yield of tomato was higher with drip irrigation (58.62 t ha^?1) than with furrow irrigation, (47.37 t ha^?1). Maximum fruit yield was recorded with 100% NPK fertigation (74.87 t ha^?1) and was associated with a higher number of fruits per plant and a bigger fruit size than the solid applied fertilizers under both drip and furrow irrigation. On average, tomato accumulated more NPK across the fertigation levels than with drip and furrow irrigation. Similarly, the more controlled application of nutrients in fertigation treatments improved NPK recovery and fertilizer use efficiency (FUE) and resulted in lesser leaching of NO₃ ^?-N and K to deeper soil layers.     

Phosphorous acid treatments control Phytophthora diseases in Australia1

Treatments with a partially neutralized formulation of phosphorous acid containing potassium phosphite were assessed for control of Phytophthora diseases in subtropical and temperate crops in Australia. In Queensland, trunk injections of phosphite (10% solution) controlled severe root rot (Phytophthora cinnamomi) of avocado trees and resulted in the recovery of trees. Single pre-harvest sprays (2.5 kg ha^-1) of phosphite controlled root and heart rot (P. cinnamomi) of pineapples. Foliar sprays of phosphite (64 g per tree) controlled root rot (P. nicotianae var. parasitica) and trunk canker (P. citrophthora) of mandarin trees. In Victoria, a foliar spray of phosphite (300 g ha^-1) reduced root rot (P. clandestina) of subterranean clover and increased dry matter by 1.96 to 5.11 t ha^-1. Trunk injections of phosphite (10% solution) controlled trunk rot (P. cactorum) of peach trees and foliar sprays (10 kg ha^-1) reduced severity of root rot (P. nicotianae var. nicotianae) of tomatoes.     

Effect of nitrogen fertilizer application on growth, biomass production and N-uptake of torpedograss (Panicum repens L.)

A glasshouse study was conducted to evaluate the effects of different rates (0, 50, 100, 200 and 400 kg ha^?1) of nitrogen (N) fertilizer application on the growth, biomass production and N‐uptake efficiency of torpedograss. The growth responses of torpedograss to the N application were significant throughout the observation periods. Torpedograss grown for 60 days obtained the highest total biomass of 23.0 g plant^?1 with an application of 200 kg ha^?1 N, followed by 20.4 g plant^?1 with an application of 100 kg ha^?1 N; when it was grown for 90 days a significantly higher biomass of 102.3–106.0 g plant^?1 was obtained with the 200–400 kg ha^?1 N than the biomass (68.0 g plant^?1) obtained with the fertilizer applied at a lower rate. When the torpedograss was grown for 130 days the highest biomass was 230.0 g plant^?1 with the 400 kg ha^?1 N application, followed by a biomass of 150.0 g plant^?1 with the 200 kg ha^?1 N application, but the above‐ground shoot in all treatments was over mature for animal food. The ratio of the above‐ground shoot to the underground part increased with the increase in N application up to 400 kg ha^?1 during the 90 days after planting (DAP), but the above‐ground shoot biomass was the same with the 200 and 400 kg ha^?1 N. The agronomic efficiency of the N application decreased to 5–38 with the increase in N application to 400 kg ha^?1, which was less than half the agronomic efficiency with the 200 kg ha^?1 N. The agronomic efficiency of N was very low (5–22) during the 60 DAP, which indicated that the N application would not be economically viable in this period for torpedograss as a pasture, and short‐duration plants could be cultivated in torpedograss‐infested fields to minimize weed‐crop competition. The nitrogen concentration (%) in the torpedograss increased with the increase in N application, but N‐uptake efficiency was the opposite and the value was very low with the 400 kg ha^?1 N. The above results lead us to conclude that the N application rate of 200 kg ha^?1 is the most effective for torpedograss growth.     

Foliar Application of Silicon,Sulfur, and Flowering Fruit Set Biostimulant on Canola

This experiment was conducted to study the effects of foliar application of silicon, sulfur, and flowering fruit set biostimulant on canola in the farmer’s condition in Darzian, 12?km from Marivan city in the northwest of Iran. The experimental layout was designed as a split-split plot in a randomized complete-block design, with three replications during two consecutive growing seasons, 2017–18 and 2018–19. The main factor included silicon application at two levels: control (0: non-application) and silicon application at 2?kg ha^?1. Sub-factor was sulfur spraying at three levels (0, 1, and 2?L ha^?1) and sub-sub-factor was Tecamin flower (Agri Tecno Fertilizantes, Valencia, Spain) spraying as a flowering fruit set biostimulant at three levels (0, 1, and 2?L ha^?1). The results of the combined analysis showed that the number of grains per pod and biomass were increased significantly at the 1% level by silicon application. Sulfur application improved 1000-grain weight, grain yield, and biomass. This increase was 7.42% for grain yield. Tecamin also significantly increased all traits, including fertile and infertile pod numbers, grain number per pod, 1000-grain weight, grain yield, and biomass. As the most important economic traits, Tecamin increased grain yield by 14.12% compared to controls. Among the treatments, the effect of Tecamin on increasing grain yield was superior. In this experiment, some traits were significantly affected by interaction effects of treatments.

     

Efficacies of low- to high-volume (960-10 700 litre ha− 1) citrus sprayers for applying petroleum spray oil to control chinese wax scale

Petroleum spray oil (2, 4 and 6% in water) was applied to Valencia orange, Citrus sinensis (L.) Osbeck, for the control of Chinese wax scale, Ceroplastes sinensis del Guercio, using a low-volume ( <2000 litre ha^?1)air-blast (LV AB) sprayer, a low- to high-volume (L-HV) (up to 7000 litre ha^?1) sprayer with four fan-assisted rotary atomiser (FARA) spray heads mounted on a vertical tower, and a high-volume (>7000 litre ha^?1) oscillating boom (HV OB) sprayer. The most effective sprayer was the L-HV FARA sprayer. The most cost-effective treatment was a 20 ml litre^?1 (60 litre oil ha^?1) spray applied at 3000 litre ha^?1 by the L-HV FARA sprayer. It gave mortality equivalent to a standard 20 ml litre^?1, 10 700 litre ha^?1 spray (214 litre oil ha^?1) applied by the HV OB sprayer but with 72% less spray and significantly less oil deposited per cm² of leaf area. Equivalent or significantly (P = 0·05) higher mortality than that given by the 10 700 litre ha^?1 HV OB spray was given by the 40 ml litre^?1, 3000 (120 litre oil ha^?1) and 60 ml litre^?1, 2180 and 3000 litre ha^?1 (130·8 and 180 litre oil ha^?1) L-HV FARA sprays, but the 60 ml litre^?1 sprays deposited more oil per cm² than the 20 ml litre^?1 HV OB spray and were considered to be potentially phytotoxic. The least effective sprayer was the LV AB sprayer, which applied a 60 ml litre^?1 spray (57·6 litre oil ha^?1) at 960 litre ha^?1. Linear relationships were established for Chinese wax scale mortality, transformed using an angular transformation (arcsin proportion), versus log₁₀ spray volume for the 20, 40 and 60 ml litre^?1 sprays applied by L-HV FARA at 1260,2180 and 3000 litre ha^?1, mortality versus log₁₀ μg oil cm^?2 and log₁₀ μg oil versus log₁₀ volume of oil sprayed.     

Sugarbeet tolerance and weed control efficacy with split applications of phenmedipham plus desmedipham

Sugarbeet and weeds were treated with phenmedipham plus desmedipham either as single applications or as split applications in which 50% of the equivalent single application rate was applied at each application. Split application did not alter the phytotoxicity to the crop when environmental conditions did not predispose the Sugarbeet to injury by the herbicide. Split applications at 1-1 or 1-4 kg ha^?1 spaced from 0-5 to c. 5 days apart caused more injury to the crop than the respective single applications when environmental conditions were such that injury to the crop resulted from the single applications. Injury to Sugarbeet following application of 0-72 kg ha^?1 of phenmedipham plus desmedipham was always low, regardless of the type of application. Susceptible weeds were controlled by single applications of 1 1-1 ?4 kg ha^?1, but 0-72 kg ha^?1 did not reliably provide adequate control. Split applications c. 3-8 days apart gave improved control. Control achieved by 0-72 kg ha^?1 of the herbicide applied as split treatments equalled or exceeded that produced by single applications of 1-4 kg ha^?1. Improvement in the control of tolerant weed species by split applications of phenmedipham plus desmedipham was species dependent. Use of low-rate split applications of phenmedipham plus desmedipham thus resulted in reduced injury to the Sugarbeet, and the introduction of less herbicide into the ecosystem, while maintaining or improving the control of susceptible weeds.     

Residualwirkung von Chlortriazin-Herbiziden im Boden an drei rumänischen Standorten. II. Prognose möglicher Folgekulturen bei Atrazinrükständen im Boden

Residual effects of chlorotriazine herbicides in soil at three Rumanian sites. II. Prediction of the phytotoxicity of atrazine residues to following crops Total and plant-available atrazine residues in the top 10 cm soil were measured 120 days after application of 3 kg ai ha^?1 to maize (Zea mays L.) at three sites in Rumania. At one site, similar measurements were made 3?5 years after application of 100 kg ai ha^?1. Plant-available atrazine residues were estimated by extraction of soil samples with water, and by bioassay using Brassica rapa as the test plant. It was calculated that between 30 and 120μg atrazine 1^?1 was potentially available to plants in the different soils. Dose-response relationships for atrazine and the most important rotational crops with maize in Rumania—sunflower, winter wheat, soybean and flax—were determined in hydroponic culture using herbicide concentrations corresponding with the plant-available fractions measured in the different soils. ED₅₀ values were determined by probit analysis and the results showed that sunflower (ED₅₀, 22μg 1^?1) was the most sensitive crop, and soybean (ED₅₀, 78μg 1^?1) was the least. The residual phytotoxicity of atrazine to succeeding crops in the different soils was predicted using the appropriate availability and phytotoxicity data, and the results showed good agreement with those observed. The results suggest that measurements of plant-available herbicide residues afford a rapid method of assessing possible phytotoxicity to following crops.     

The fungicide tridemorph as a selective herbicide for the control of Holcus lanatus in ryegrass and of Bonus sterilis in barly

The potential of the fungicide tridemorph selectively to control established plants of Holcus lanatus L. in ryegrass (Lolium perenne L) and Bromus sterilis L. in barley (Hordeum vulgare L.) was examined in glasshouse trails. A dose of 4.2 kg ha^?1 tridemorph gave selectively between H. lanatus and ryegrass similar to, but more costly than, that which would be provided by 1.2 kg ha^?1 asulam. B sterilis was more sensitive to tridemorph than was barley. Two additives, glycerol and the oil-surfactant mixture ‘PF’ enhanced this selectivity when tridemorph was applied at 2.1 kg ha^?1.     

Physiological interactions between the herbicide EPTC and selected analogues of the antidote naphthalic anhydride on two hybrids of maize

The efficacies of nine structural analogues of the herbicide antidote naphthalene-1,8-dicarboxylic acid anhydride (naphthalic anhydride, NA) for the protection of maize (Zea mays L. cv. DeKalb XL72AA and DeKalb XL67) against injury by the herbicide S-ethyl dipropyl(thiocarbamate) (EPTC) were elevated under greenhouse conditions. The chemical analogues of NA tested were: acenaphthenequinone (ACQ); 4-aminonaphthalene-1,8-dicarboxylic acid anhydride (NH₂NA); 1,8:4,5-naphthalenetetracarboxylic acid dianhydride (NDiA); naphthalene- 1,8-carboximide (NHNA); 4-chloronaphthalene-1,8-dicarboxylic acid anhydride (C1NA); biphenyl-2,2′-dicarboxylic acid anhydride (diphenic anhydride; DA); 2-phenylglutaric anhydride (PGA); phthalic anhydride (PHA); phenalen-1-one (PA). Pre-plant incorporated applications of EPTC at 2.2, 4.5, 6.7, and 9.0 kg ha^?1 were highly toxic to XL67 maize. Appreciable injury to XL72AA maize by EPTC was observed only with the high rates of EPTC (6.7 and 9.0 kg ha^?1). Of the analogues tested PGA and PA were very toxic and inhibited germination of both maize hybrids. NA, ACQ, NH₂NA, NDiA, NHNA, C1NA, DA, and PHA applied as seed dressings at 5.0 and 10 g per kg of seed offered satisfactory protection to XL72AA maize against EPTC rates higher than 6.7 kg ha^?1. The same antidotes significantly antagonised the EPTC activity against XL67 maize but the overall protection obtained was partial and not agronomically important. The presence of the dicarboxylic anhydride group and of at least one aromatic ring attached directly to the anhydride appeared to be essential for the exhibition of protective activity by the structural analogues of NA. NA was slightly toxic to both hybrids of maize and chlorination of NA increased the phytotoxicity of this molecule. A genetic component that is present in the thiocarbamate-tolerant XL72AA hybrid but absent from the thiocarbamate-susceptible XL67 hybrid of maize appeared to be important for the phytotoxic activity of EPTC and may be involved in the protective activity of NA and its structural analogues.