Tag Archives: weed infestation

103-112 E. Stasinskis
Effect of preceding crop, soil tillage and herbicide application on weed and winter wheat yield
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Effect of preceding crop, soil tillage and herbicide application on weed and winter wheat yield

E. Stasinskis

LLU, Faculty of Agriculture, Department of Soil Management, Liela iela 2, Jelgava, LV-
3001, Latvia, e-mail: eriks@dobeleagra.lv

Abstract:

This article describes results obtained in three years of experiments (2001–2003) carried out at farm Dobele Agra SIA located in the Dobele region of Latvia. Trials were established in two different crop rotations (Factor A): 1. winter wheat sown after winter wheat, 2. winter wheat sown after winter rape. Three different soil tillage and sowing methods were compared (Factor B): 1. – minimal conservation soil tillage in 10–15 cm deep with mixing of soil; 2. – direct sowing into stubble without any previous soil cultivation; 3. – traditional soil tillage with ploughing on 25 cm with cultivation before sowing. Additionally we compared the impact of those soil tillage methods on weed infestation in winter wheat (Factor C): 1. – using herbicide Secator 0.3 kg ha-1, 2. – without herbicide treatment. A significantly smaller total number of weeds was observed in treatments where winter wheat was grown in recurrent sowing, primarily caused by differences in numbers of oil seed rape in this treatment. A significantly smaller number of weeds was also observed after traditional soil tillage with ploughing. Data analysis shows significant linear negative correlation between winter wheat yield and the number of total weed infestation and several weed species – Stellaria media (L.) Vill., Sinapis arvensis L., Matricaria perforata Merat. and Lamium purpureum L. The highest impact on changes of winter wheat grain yield was made by herbicide use – 64.1%

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281-285 S. Maiksteniene and A. Arlauskiene
The effect of agricultural management systems on the weed incidence in cereals
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The effect of agricultural management systems on the weed incidence in cereals

S. Maiksteniene and A. Arlauskiene

Joniskelis Research Station of the Lithuanian Institute of Agriculture, Joniskelis,LT-39301 Pasvalys District, Lithuania; e-mail: joniskelio_lzi@post.omnitel.net

Abstract:

Two field trials were carried out at the Lithuanian Institute of Agriculture’s Joniskelis Research Station on an Endocalcari-Endohypogleyic Cambisol. The experiments were designed to identify the effects of legume pre-crops and intercrops as well as the impact of their biomass incorporated as green manure on the weed incidence in succeeding cereals. The effects of legume pre-crops red clover, sown lucerne, and vetch and oats mixture on the incidence of weeds were determined by their weed incidence and the cereal crop’s suppressive power that formed under its effect. Undersown intercrops (Trifolium pratense L., Lolium multiflorum Lam., Dactylis glomerata L.), reduced the number of weeds in cereals (on average 13.9%). During the cereal post-harvest period red clover performed best at suppressing weeds, and its positive effect persisted in the year following incorporation of intercrops biomass. The effect of intercrops as post-crops (Raphanus sativus L., Sinapis alba L.) on weed incidence in the cereal crop depended upon the weather conditions that determined intercrop emergence time and intensity of plant development.

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441-445 A. Velykis and A. Satkus
Influence of crop rotations and reduced tillage on weed population dynamics under Lithuania’s heavy soil conditions
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Influence of crop rotations and reduced tillage on weed population dynamics under Lithuania’s heavy soil conditions

A. Velykis and A. Satkus

Joniskelis Research Station of the Lithuanian Institute of Agriculture, Joniskelis, LT-3930,Pasvalys District, Lithuania; tel.fax.: 370-71-38224; e-mail: joniskelio_lzi@post.omnitel.net

Abstract:

Experiments to study the weed population dynamics in cereals, under conditions of expanded winter crop proportion in rotations and reduced soil tillage, were carried out on a clay loam Gleyic Cambisol at Joniskelis Research Station of the Lithuanian Institute of Agriculture. Variations were as follows: A. Crop rotations with different proportions of winter and spring crops: 1. Without winter crops; 2. Winter crops 25%; 3. Winter crops 50%; 4. Winter crops 75%; 5. Winter crops 100%, growing annual and perennial grasses, spring and winter wheat, triticale and barley; B. Soil primary tillage systems: 1. Conventional (ploughing). 2. Reduced (ploughing after grasses, ploughless after cereals) were investigated. The results of investigations show that increasing the proportion of winter crops in rotations during a four-year rotation resulted in reduction of perennial weeds in the cereal crops; however, the content of annual weeds was higher. The prevalent annual and perennial (14.7% of total number) weeds spread in spring cereals (wheat, triticale, barley) were more dangerous to crops than to the weed species found in winter cereals. Perennial weeds amounted to only 6.9% in winter cereals. The perennial weeds recorded in cereals were only 3.9-18.0% at the beginning of crop growing season, depending on crop rotation, however before crop harvest they reached 24.2−52.1%. When growing cereals with reduced soil tillage, the number of perennial weeds was 2.4 times higher; annual weeds, somewhat lower, and the air-dried biomass of all weeds was 44.5% higher compared to conventional tillage.

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91–98 K. Pranaitis and S. Marcinkonis
Effect of stubble breaking and ploughing at different depths on cultivation of peas
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Effect of stubble breaking and ploughing at different depths on cultivation of peas

K. Pranaitis and S. Marcinkonis

Voke branch of the Lithuanian Institute of Agriculture, Žalioji aikštė 2, Trakų Vokė,
LT-02232 Vilnius; e-mail: kestas.pranaitis@voke.lzi.lt

Abstract:

Field trials were conducted over the period 1998–2001 at the Voke Branch of the Lithuanian Institute of Agriculture on a sandy loam Haplic Luvisol (LVh). Pea’s precrop was winter rye. Crop residues were returned to the soil; straw was chopped at harvest. The aim of the investigation was to determine the effect of stubble breaking, ploughing at different depths on the weediness of cultivated crop, as well as on the crop yield.
Most couch-grass (Elytrigia repens (L.) Nevski) infested were unbroken-stubble and shallow-ploughed plots. It caused a yield reduction by 11–20%. The lowest numbers of weeds were counted and the highest pea’s yield was obtained on broken stubble, 0.22–0.25 m depth ploughed.

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