Ireneusz Sosna

Wrocław University of Environmental and Life Sciences


Excessive amount of fruits on a tree results in loss of their weight. An advantageous way of improving the quality of e.g. plums is thinning their fruitlets. The experiment involving this problem was conducted in the years 2003–2005 at the Fruit Experimental Station in Samotwór near Wrocław. The subject of investigation were 10-year-old plum trees of two cultivars – ‘Valor’ and ‘President’, growing on a ‘Myrobalan’ rootstock (Prunus divaricata) in the spacing of 4 × 3 m (833 trees./ha). In the course of three subsequent years fruitlets were hand thinned one and two month after full blooming, as well as chemically treated, using the following preparations: Pomonit R-10 (NAA) + Ethrel (ethephon) and exclusively with Ethrel (14–10 days after trees blooming respectively). As a control there served trees which did not undergo fruitlets thinning. Hand thinning increased mean weight of ‘President’ fruits, while in ‘Valor’ cv. the same dependence was
observed only when the treatment took place later. Chemical thinning did not significantly affect on fruit yield quality. In both plum cultivars, fruits obtained from not thinned trees characterized similar content of soluble solids and mineral components to those produced after application of hand and chemical thinning.


Prunus domestica, NAA, ethephon, chemical composition

Basak A., Rechnio H., Cegłowski M., Guzowska-Batko B., 1993. Plum fruit thinning with ethephon, paclobutrazol and mixture of NAA, ethephon and carbaryl. J. Fruit Ornam. Plant. Res. 1(2), 35–43.
Buler Z., Mika A., Krzewińska D. Treder W., Sopyła B., 2006. Effect of three training systems and hand fruitlet thinning on yield and fruit quality in two cultivars of Japanese plum (Prunus salicina Lindl.). J. Fruit Ornam. Plant Res. 14, 125–134.
Byers R.E., Costa G., Vizzoto G., 2003. Flowers and fruit thinning of peach and other prunus. Hort. Rev. 28, 351–392.
Day K.R., DeJong T.M., 1999. Improving fruit size: thinning and girdling nectarines, peaches and plums. Compact Fruit Tree 32(2), 49–51.
Drkenda P., Bertschinger L., 2006. Chemical thinning of some new high-quality plum cultivars. Acta Agric. Slovenica 87(2), 311–323.
Drkenda P., Bertschinger L., Stadler W., 1998. Fruit load and fruit quality of high yielding plum cultivars. Obst- und Weinbau 134(6), 156–158.
Drkenda P., Bertschinger L., Stadler W., Schwitzer T., 2006. Manual fruit thinning at ’Elena’ plum cultivar for the purpose of fruit quality regulation. Works of the Faculty of Agric. Univ. Sarajevo 57(2), 45–52.
Gonkiewicz A., Nosal K., 2006. Przerzedzanie zawiązków owocowych śliwy Prunus domestica L. odmiany Stanley z zastosowaniem soli potasowej kwasu alfa naftylooctowego. Acta Agr. Silv. ser. Agr. 48, 97–105.
Grajkowski J., Ochmian I., Mikiciuk G., Chełpiński P., Skwarska I., 2004. Wpływ chemicznego i ręcznego przerzedzania zawiązków śliwy odmiany ‘Królowa Wiktoria’ na wielkość i jakość plonu. Folia Univ. Agric. Stetin., Agricultura 234(93), 119–122.
Gupta M., Kaur H., 2007. Effect of growth regulators on pre-harvest fruit drop in plum (Prunus salicina L.). Indian J. Hort. 64(3), 278–281.
Harangozo T., Szabo Z., David M., 1996. Chemical thinning of plum varieties. Hort. Sci. 28(1/2), 35–39.
Jacob H.B., 1998. Fruit regulation in plums, prunes and damsons. Acta Hort. 478, 127–136.
Johnson R.S., Andris H., Day K., 2002. Experiences with chemical thinning of plums. Proc. Utah State Hort. Association, 1–3.
Krška B., Močička M., 2001. The effect of various methods of thinning on the quality of apricot fruits. Hort. Sci. 28(3), 106–111.
Lipecki J., Janisz A., 2007. Wpływ ręcznego przerzedzania zawiązków na jakość owoców śliwy. Annales UMCS, Horticultura 17(1), 1–8.
Lipecki J., Janisz A., Szember E., Sienkiewicz P., 2001. Skład chemiczny owoców kilkudziesięciu odmian śliw. Zesz. Nauk. ISiK – Skierniewice 9, 243–250.
Meland M., 2004. Response of ‘Victoria’ plums to chemical bloom thinning. Acta Hort. 636, 275–281.
Meland M., Birken E., 2010. Ethephon as a blossom and fruitlet thinner affects crop load, fruit weight and fruit quality of the European plum cultivar ‘Jubileum’. Acta Hort. 884, 315–321.
Plich H., Lewandowski M., 2005. Wpływ przerzedzania zawiązków i modyfikacji składu atmosfery w czasie przechowywania na produkcję etylenu i trwałość śliwek po zbiorze. Zesz. Nauk. ISiK – Skierniewice 13, 93–99.
Son L., 2004. Effects of hand and chemical thinning on fruit size and quality of ‘Priana’ and ‘Beliana’ apricot (Prunus armeniaca) cultivars. New Zealand J. Crop Hort. Sci. 32(3), 331–335.
Stadler W., Widmer A., Bertschinger L., 2004. News on fruit bearing control in integrated and organic plum production systems. Obst- und Weinbau 140(5), 11–14.
Stern R.A., Flaishman M., Ben-Arie R., 2007. Effect of synthetic auxins on fruit size of five cultivars of Japanese plum (Prunus salicina Lindl.). Scientia Hort. 112, 304–309.
Webster A.D., Spencer J.E., 2000. Fruit thinning plums and apricots. Plant Growth Regulation 31, 101–112.
Wieniarska J., Basak A., Murawska D., Szember E., 2000. Wstępne wyniki doświadczeń z przerzedzaniem zawiązków śliwy przy użyciu różnych preparatów. Zesz. Nauk. ISiK – Skierniewice 8, 191–198.
Zhang X.Y., Luo J., Ye Z.W., 2002. Effect of ethephon on delaying blooming date in plum. Acta Agric. Shanghai 18(2), 42–44.


Ireneusz Sosna 
Wrocław University of Environmental and Life Sciences



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