Tag Archives: damage

55–62 R. Sestras, E. Tamas and A. Sestras
Morphological and genetic peculiarities of fruits in several winter apple varieties which confer resistance to damage
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Morphological and genetic peculiarities of fruits in several winter apple varieties which confer resistance to damage

R. Sestras¹, E. Tamas¹ and A. Sestras²

¹University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, No. 3-5 Manastur St., 3400 Cluj-Napoca, Romania; e-mail: rsestras@email.ro
²Horticultural Research Station, 3-5 Horticultorilor St., Cluj-Napoca, Romania

Abstract:

Among 15 winter apple varieties studied for their resistance to the damage of fruits, Golden Delicious was susceptible to fruit injury, while the Florina, Idared and Granny Smith can be considered resistant to pricking, cutting and hitting of the fruits. The variability of the morphological characteristics of the fruits was relatively low, the fruit volume being averagely variable and the fruit resistance to injury being the character with the highest variability (s% = 26.4). The resistance of the fruits to injury was not correlated with their height, diameter, weight, shape and volume. The characteristics of the fruits have a strong genetic determinism, but the additive effects of the genes do not play the most important role in all cases. For the fruit resistance to injury the big differences between heritability coefficients values in a broad and narrow sense signify the fact that the resistance to injury of apples is influenced not only by additive effects but also by the dominance and epistasis effects of the genes.

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123–130 K. Hiiesaar, L. Metspalu, P. Lääniste and K. Jõgar
Specific composition of flea beetles (Phyllotreta spp ), the dynamics of their number on the summer rape (Brassica napus L. var. oleifera subvar. annua) Mascot
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Specific composition of flea beetles (Phyllotreta spp ), the dynamics of their number on the summer rape (Brassica napus L. var. oleifera subvar. annua) Mascot

K. Hiiesaar¹, L. Metspalu¹, P. Lääniste² and K. Jõgar¹

¹Institute of Plant Protection, Estonian Agricultural University, Kreutzwaldi 64, 51014, Tartu, Estonia; e-mail: hkelli@eau.ee
²Institute of Field Crop Husbandry, Estonian Agricultural University, Kreutzwaldi 64, 51014, Tartu, Estonia

Abstract:

The specific composition of the flea beetle Phyllotreta spp (Coleoptera: Chrysomelidae), time of its appearance and dynamics of its number on the summer rape cultivar Mascot were determined. During the observation period, 6 species of flea beetles were found: Phyllotretaundulata  Kutsch., Ph. nemorum L.,  Ph. vittata  (Ph. striolata), Ph. nigripes F. Ph. atra and Ph. vittula. First flea beetles appeared at the time of the sprouting of rape plants. In the course of the entire observation period, the most numerous of these was the small striped flea beetle Ph. undulata. Proportion of the other species not often exceeded 10%. Very warm and dry weather following the sprouting of plants caused a rapid increase in the number of the pests and the maximum number was reached in a short time. A somewhat larger number of beetles was found on the edge plots. The field was sprayed three times, using Fastac (alphacypermethrin). Although after the first spraying the number of pests had decreased to almost zero, one week later the number of beetles began to rise again. Ten days after the spraying, the number of pests in the control and the sprayed variant had become equal, 2.0 and 2.2 individuals per plant. The second spraying lowered the number of pests again  down to zero. At that time the plants were reaching the stage of  3-4 true leaves, the time when the growth rate is the fastest. The third spraying was primarily directed against pests damaging generative organs: pollen beetles and weevils, and at that time plants began to form secondary racemes, and primary racemes lengthened. For controlling of flea beetles spraying was no more necessary.

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17–29 K. Hiiesaar, L. Metspalu, P. Lääniste, K. Jõgar, A. Kuusik and J. Jõudu
Insect pests on winter oilseed rape studied by different catching methods
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Insect pests on winter oilseed rape studied by different catching methods

K. Hiiesaar¹, L. Metspalu¹, P. Lääniste², K. Jõgar¹, A. Kuusik¹ and J. Jõudu²

¹Department of Plant Protection, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia; e-mail: hkelly@eau.ee
²Department of Field Crop Husbandry, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia

Abstract:

The distribution, species association and number of pest insects on winter oilseed rape of varieties ‘Wotan’ and ‘Express’ were studied in field experiments. Three catching methods were used: black plastic basins on the soil surface between plants, yellow flight traps filled with water at the height of the crop canopy and the shaking of plants above a plastic basin. The most abundant pest species was the pollen beetle,Meligethes aeneus, while the number of individuals from the species M. virescens in traps was much lesser. The other  important group of pest insects were weevils Ceutorrhynchus spp., the most common of which was the cabbage seed weevil, C. assimilis.  Three species of flea beetlesPhyllotreta undulata, Ph. vittata and Ph. nemorum were typical contents of traps during May. In the last decade  of May, there was a large number of thrips (Thysanoptera, Tripidae) in traps.
Winter oilseed rape began to flower to some extent later, when pest insects of cruciferous plants had ended their hibernation. Therefore, the pests first inhabited weeds and already flowering plants, from where they later moved onto winter oilseed rape.
    In the field of winter oil seed rape, chemical pest control with a pyrethroid, Fastac, did not significantly influence the abundance of  pest insects. In the last decade of May, the total number of beetles in all test variants was relatively small, but, at the beginning of June, it increased almost to an equal extent. On the basis of flight traps, heavy damage of pods could be assumed, however, only a few larvae fell into traps on the soil surface, and virtually no damaged pods were detected. Thus the spraying with Fastac had no significant effects on the number of insects caught in traps.

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