Selectivity of the sulfonylurea herbicide group in the crop of maize inbred lines

The selectivity of the nicosulfuron, primisulfuron-methyl and rimsulfuron herbicides in relation to 20 PL maize inbred lines was monitored. Obtained results were compared with the untreated control. The following parameters were measured during the growing period: plant height (cm): ear height (cm) leaf width at the ear bottom (cm): tassel length (cm); number of primary tassel branches; grain yield at the and of growing season (t/ha) and grain moisture percentage (%). The effects of applied herbicides on observed maize inbred lines showed different degrees of selectivity. Average values of estimated parameters for all studied inbreeds differed significantly over applied herbicides. Nicosulfuron was most selective.

Effect of Fomesafen on the abundance of soil microorganisms in soybean crop

Effect of the herbicide Fomesafen on the abundance of soil microorganisms was investigated. The abundance of total microflora, fungi, actinomycetes aerobic nitrogen fixing bacteria (Azotobacter) and cellulolytic bacteria was studied. Trials were set up on smonitza and alluvium soil types in laboratory environment. Fomesafen was applied at 0.2 and 0.4 kg/ha rate. Microbiological analysis was done 1, 3, 7, 14, 30 and 60 days after treatment. The acquired results showed that fomesafen had caused a decrease in the abundance of total microorganisms, aerobic nitrogen fixing bacteria and cellulolytic bacteria, the highest effect being recorded in the interval between the 7th and 14th post-treatment days. The most susceptible genus was Azotobacter. Fomesafen was found to cause an increase in the abundance of actinomycetes, while no shangein fungi abundance was recorded. No difference in the intensity of effect on the investigated parameters was found between the applied rate and soil type, except a 36% reduction of total microorganisms on smonitza and 51% on alluvium, and 48% reduction of cellulolytic bacteria on smonitza and 41% on alluvium.

Control of some sunflower pests by seed treatment

During 2000 and 2002, several assays were carried out to study efficacy of insecticide treatment of sunflower seeds against soil pests (larvae of the Elateridae and Scarabaeidae families) and the corn weevil (Tanymecus dilaticollis Gyll). Used in the trials were the following insecticides thiamethoxam, thiamethoxam + tefluthrin, carboturan, fipronil and imidacloprid, and in first year granulated forat and liquid carbosulfan lindan. The parameters for evaluation of insecticides efficacy were stand density and the percentage of plants damaged by corn weevil. Majority of tested insecticides provided significantly higher stand density in relation to untreated control, so that can be used for dressing of sunflower seeds against soil pests under modest to middle populations. The most prospective are thiamethoxam, imidacloprid and carbofuran, that contain systemic properties and can protect young plants from pests of the above ground during early spring.

Omnimite 500 efficacy studies in control of Panonychus ulmi Koch

In the paper are given efficacy study results of the pesticide Omnimite 500 (a.i. propargiet) in control of Panonychus ulmi Koch on the apple of Ajdared variety. Studies were performed in two localities, Beska and Irmovo. Treatment was performed twice in 15 days period in June and July 2002. Very significant initial population was previously monitored. Evaluation shows high efficacy in all four replications. In apple orchards in the locality Beska, in regard to standard, average efficacy was 94.06. In apple orchards in the locality Irmovo efficacy was in average higher, i. e. 98.11%.

Malathion and Deltamethrin efficacy in controlling Acanthoscelides obtectus say weevil during long storage of beans

Efficacy of Malathion and Deltamethrin contact insecticides in controlling Acanthoscelides obtectus Say bean weevil over a period of 12 months following treatment in laboratory conditions (simulating storage conditions) was investigated. Using appropriate methods (EPPO and other), beans were treated with recommended amounts of Malathion - and Deltamethrin-based insecticide powders. Over a period of 12 months, bioassay was used to determine A. obtectus adult mortality after 2, 7 and 14 days of contact with treated material. Additionally, potential occurrence of F1 generation progeny was monitored over the 14 days of contact with insecticides. The results show that, regardless of the age of Malathion and Deltamethrin deposits, two and seven days of contact with treated beans was insufficient to achieve full mortality of bean weevils, while their mortality was total (100%) after 14 days of contact, the only exception being a Malathion deposit aged 240 days and Deltamethrin deposit aged 90 and 360 days. After 14 days of contact with all Malathion and Deltamethrin deposits on beans and additional 7 days of recovery on untreated material, the mortality of bean weevil adults was total. Weevil adults of F1 generation were found only on Malathion deposits aged 240 and 360 days, while no progeny was registered on Deltamethrin deposits. The tested contact insecticides, applied as powder formulas, can provide full protection of beans from weevils over a 12-month storage period.

Sensitivity of Botrytis cinerea Pers. isolates from different hosts to Dicarboximides

A total of 106 isolates of B. cinerea, originating from strawberry and raspberry fruits, grapes, and leaves of lettuce, were studied for resistance to iprodione and vinclozoline. Based on initial growth on PDA containing 10 mg/L iprodione or vinclozoline, the isolates were classified into four categories: resistant, low-sensitive, medium-sensitive, and high-sensitive to these fungicides. The isolates are considered resistant if they start growing simultaneously on both fungicide amended and fungicide free medium (up to two days after their transfer). Low-sensitive are those isolates whose growth starts between 2nd and 4th day after the transfer onto fungicide amended medium. The isolates are regarded as medium-sensitive if they start growing in five to twelve days on the same medium. High-sensitive isolates do not grow on fungicide amended medium up to twelve days after the transfer. The isolates expressed high sensitivity to both iprodione and vinclozolyie. The largest portion of all the isolates tested (68.9%) was classified as high-sensitive to iprodione, while resistant isolates were not recorded whatsoever. Moreover, none of the isolates from strawberry (Preljina locality), raspberry, and grapevine were classified as low-sensitive to iprodione whereas 6% of the isolates from lettuce belonged to this category. Similar results were obtained in the case of vinclozoline. As much as 77.4% of the isolates were highly sensitive to vinclozoline. In addition, resistant isolates were not noticed at all. Twelve per cent of the isolates from lettuce were of low sensitivity, but there were no isolates from strawberry (Preljina locality), raspberry, or grapevine attributed to this category.

Mesotrione: A new herbicide for use in maize

In 2000 and 2001 field trials were carried out to evaluate the efficacy of herbicide mesotrione in maize. The experiments were established in Zemun Polje and Smederevska Palanka, according to EPPO/OEPP standard methods. Trade formulation Callisto (a.i. mesotrione 480 g/L) used as a experimental sample in two doses 0.15 L/ha and 0.25 L/ha for pre-em, and 0.15 L/ha adjuvant; 0.25 L/ha + adjuvant and 0.25 L/ha alone for foliar application. The most sensitive weed species were: Adonis aestivalis, Amaranthus retroflexus, Cirsium arvense, Chenopodium album, Chenopodium hibridum Lepidium draba, Brassica nigra, Datura stramonium, Kickia spuria, Polygonum lapathifolium, Sinapis arvensis, Solanum nigrum, Stachys annua i Xanthium strumarium.

Biological control in crop protection: Problems and perspectives

The idea of fighting pathogens, pests, and weeds by biological measures is not new. Only recently, however, has the need for this aspect of crop protection and related bioproducts arisen. Increasingly stricter legislation concerning pesticides and new information about their potential harmfulness have narrowed the scope of products, offered by large agrochemical companies, thus reducing the prospects of successful and profitable crop protection. In addition, there has been a high risk of resistance of harmful organisms to classical pesticides which throws new light on problems that the industry of chemical pesticides encounters. The control of harmful insects by bioproducts has been a matter of utmost interest, mainly due to a relative success of products, based on Bacillus thuringiensis. However there has been a few more successful attempts of developing biological fungicides, nematocides, and herbicides in the last decade. Still, crop protection products, based on living organisms, represent a small portion of total pesticide industry which amounts to approximately 32 billion dollars per year (Warrior, 2000). The majority of living organisms, been investigated with purpose of biological control, belongs to fungi, bacteria, or arthropods. Commercially, the number of those applied in biopesticides is small, especially because of limitations, imposed on reproduction and stability of organisms in storage and formulation of biopesticides. The aim of this paper is to describe the status of biological control in crop protection, problems encountered, and perspectives of its future development.

Efficiency of more recent fungicides in control of apple scab and powdery mildew

Apple scab (V. inaequalis) and powdery mildew (P. leucotricha) are most economicaly important diseases of apple. Chemical measures are of the highest importance in controlling these diseases. There is great number of fungicides on the market. Fungicide choice and time of application depend upon mechanism of their action. Experiments on controlling apple scab and powdery mildew are carried out in 1998/99 and 2002. in different locations in Vojvodina. According to the obtained results the highest efficacy in the control of apple scab and powdery mildew have performed pesticides from strobilurin group (Stroby-kresoxim-methyl and Zato 50 WG-trifloxystrobin)as well as fungicides belonging to the new group of fungicides (Clarinet). In the disease control of the apple high efficacy have also performed DMI fungicides such as Score 250-EC (in control of apple scab). Topas-lOOE and Webeton (in control of powder) mildew). Lower efficacy have performed fungicides with preventive activity such as combination of Venturin S-50+Cosan. Unpublished data from previous studies (1995-1997) of the fungicide Chorus (cyprodinil) biological efficacy also suggested that this new generation fungicide from anylopyrimidin group showed better efficacy than fungicides belonging to former DMI fungicides, as well as contact ones.

Absorption, translocation and metabolism of the sulfonylurea herbicides in plants

Absorption, translocation and metabolism are processes affecting the efficacy of sulfonylurea herbicides. These processes contribute significantly to selectivity but are also known to effect the development of plant resistance to this group of herbicides. Sulfonylureas may be absorbed by both ground and above ground plant parts. The level of absorption depends on numerous factors such as: development stage of the plant, ambient temperature, soil humidity, fertilizers added to herbicides, application in combination with other herbicides, sufactants, plant cultivars, mode of herbicide application, various additives. Having been absorbed, the herbicide moves to the place of action whereby the direction of translocation depends on the mode of absorption. Foliary absorbed sulfonylureas are primarily basipetally translocated. Acropetal translocation is correlated to root absorption. In addition, some herbicides belonging to this group are translocated in both directions. The level and rate of translocation depend on: soil humidity, antagonistic effect of other herbicides (in case of application of herbicide combinations), additives, fertilizers etc. Sulfonylureas in plants are subjected to different metabolic changes which mostly contribute to the inactivation. These transformations are considered to be catalyzed by the cytochrom P-450 monooxigenase enzymic system. Eventually, this process is also known to be affected by numerous factors such as: temperature, soil humidity, plant cultivars, mixtures with other pesticides etc.