Magdalena DZIÊGIELEWSKA* and Gra yna KAUP*

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1 ECOLOGICAL CHEMISTRY AND ENGINEERING A Vol. 15, No Magdalena DZIÊGIELEWSKA* and Gra yna KAUP* EFFECTIVENESS OF CHEMICAL CONTROL OF THE HORSE-CHESTNUT LEAF MINER WITH INSECTICIDES FROM THE GROUP OF CHITIN BIOSYNTHESIS INHIBITORS WITH THE USE OF METHODS OF SOIL APPLICATION AND MICROINJECTION SKUTECZNOŒÆ CHEMICZNEGO ZWALCZANIA SZROTÓWKA KASZTANOWCOWIACZKA INSEKTYCYDAMI Z GRUPY INHIBITORÓW BIOSYNTEZY CHITYNY METOD DOGLEBOWEJ APLIKACJI I MIKROINIEKCJI Summary: Microinjections and spraying trees with preparations of acyl urea compounds are enumerated among the most effective methods of combating the horse-chestnut leaf miner. The goal of the present study was to compare the effectiveness of combating the horse-chestnut leaf miner with insecticides from the group of chitin biosynthesis inhibitors based on imidachloprid through soil application or injections of the preparation directly into a tree trunk. The observations were carried out in the period of in selected green areas of Szczecin. On the basis of the carried out research a diverse degree of the disease caused by the leaf miner was stated in the trees which underwent microinjection. It differed depending on their age. The degree of the disease did not exceed 30 % in older trees (trunk diameter approx mm) and 15 % in younger trees (trunk diameter approx. 700 mm). Horse-chestnuts watered with insecticide ProAgro 100 SL (imidachloprid) in an experimental plot showed a positive reaction to the performed treatment. In the lower part of the tree crown, where a higher degree of the disease caused by the horse-chestnut leaf miner is usually noted, only low percentage of the damage was observed (up to 15 % in the first year of the observation). It results from the obtained data that the soil application of the chemical preparation may be an alternative method to spraying and microinjection. Keywords: the horse-chestnut leaf miner, insecticides of chitin biosynthesis inhibitors, chemical method A number of issues are involved in plant protection in cities where special safety precautions must be taken during sanitary treatment. The size and location of trees, * Faculty of Environmental Management and Agriculture, University of Agriculture, Department of Plant Protection, ul. J. S³owackiego 17, Szczecin, tel , fax , entomology@agro.ar.szczecin.pl, gkaup@agro.ar.szczecin.pl

2 254 Magdalena Dziêgielewska and Gra yna Kaup often along urban traffic routes, make spraying difficult despite the effectiveness of chitin biosyntethesis inhibitors [1, 2]. Both the insecticide that would successfully control phytophages in the urban situation and its application must be selected with regard to human and environmental safety, including beneficial organisms that play an important role in sustaining the biological balance in nature. While microinjections avoid the majority of these hazards, repeatedly drilled inlet holes damage trees that respond with necrosis [3, 4]. The horse-chestnut leaf miner (Cameraria ohridella) is at present the most dangerous pest of the common horse chestnut in Europe. It causes a decline in tree vigour and accelerates the plant death. Microinjections as well as soil and foliar applications of systemic neonicotinoid insecticides are believed to be some of the most effective control methods [5, 6]. The aim of the studies was to compare the effectiveness of horse-chestnut leaf miner control with the soil application method and direct tree injections with Imidacloprid insecticide. Observations were carried out in selected town greens in Szczecin in 2005 and Material and methods Observations of horse-chestnuts (Aesculus hippocastanum L) were conducted in three transects located in Szczecin (Table 1). Pilot microinjections were performed by the Public Utility Company in Szczecin on 15 April Injections were used on trees of various age on the city outskirts. ProAgro 100 SL, a systemic insecticide (Imidacloprid active ingredient), was applied in the soil in transect 3 on selected horse-chestnut trees. The insecticide was applied at 2.8 g per 1 cm of the diameter at breast height. A water solution of the agent was introduced into the root system with the use of watering on 20 th May 2004 at an air temperature of 15 o C. The effectiveness of the treatment was examined in the following years. Leaf damage caused by C. ohridella was assessed between March and October in all the transects every two weeks. The degree of leaf infection was calculated for each tree based on 20 leaves randomly collected from the lower part of the crown using the 7-degree scale by Gilbert and Gregoire [7]: 1:0 2 %, 2:2 5 %, 3:5 10 %, 4:10 25 %, 5:25 50 %, 6:50 75 %, 7: %. Transect description: horse-chestnut vigour in selected sites in Szczecin Table 1 Transect Transect location no. 1 J. Kasprowicz Park retention tank 2 ul. Boryny 3 ul. J. S³owackiego 17 Number of trees Transect description Control transect. Town green in the centre of the Kasprowicz Park, around a retention tank Transect microinjection. Town green located in the SW part of the town, on the outskirts Transect soil application. Town green near buildings of the University of Agriculture, close to a traffic route

3 Effectiveness of Chemical Control of the Horse-Chestnut Leaf Miner Results and discussion Plantings of horse-chestnuts located within the city or town borders cannot be closed off during chemical treatment, making tree spraying difficult for technical reasons. The effectiveness of microinjections, on the other hand, depends on the date of treatment as well as the age and condition of trees [6]. The analysis of leaves collected from horse-chestnuts treated with microinjections revealed the third degree of leaf infection by the miner. Between 25 and 70 % of damaged leaf blade was recorded in the treatment year (Fig. 1a, b). In Austria the evaluation of tree-injection treatments showed that dispersion of the insecticidae within the tree was very limited, the active ingredient reaching only some parts of the treated a) 80 [%] leaf miner damage [%] leaf miner damage b) control microinjection/trees 1000 mm in diameter microinjection/trees 700 mm in diameter soil application control microinjection soil application year year Fig. 1. Horse-chestnut damage caused by Cameraria ohridella in the study transects

4 256 Magdalena Dziêgielewska and Gra yna Kaup trees. However, on branches that were successfully impregnated, efficacy of treatment persisted for more than 2 years [8]. The ineffectiveness of the agent in the treatment year is also reported by abanowski and Soika [9]; they nonetheless recommend the method based on the positive results obtained in year 2 and 3 of their studies. The infection after microinjections was up to 30 % for trees having a larger circumference and 15 % for younger trees (diameter at breast height ca. 700 mm) in 2005 (fig.1ab) whereas up to 20 % of leaf damage by C. ohridella was reported in However, no damage in a half of a tree or on individual branches was frequently noted (Fig. 1a, b). This may indicate an uneven flow of the agent through vascular bundles in the tree. Although abanowski [2] reports that callus formation in wounds caused by drilling is rapid and no negative influence on the tree over a period of three years was recorded, the present observations do not confirm these findings. Closely distributed holes drilled in the trunk that are still visible well in the third year of the observations argue against the method. Pathological swellings and changes can be seen on the trunks, and stoppers for inlet holes are often removed by undesired parties as early as in the treatment year. Moreover, pathological symptoms induced by the fungus Guignardia aesculi, causative organism of the horse-chestnut leaf blotch, recognisable by leaf browning and drying, were observed, which means that microinjections do not fully protect trees from fungal diseases [10,11]. Numerous data confirm the effectiveness of watering with Imidacloprid agents to control tree insects [6, 12, 13]. The method is commonly used to control, for instance, the hemlock woolly adelgid (Adelges tsugae) in the US [14]. Positive results in leaf miner control by watering with Confidor WG 70 were obtained in Germany by Lohrer et al. [15]. However, Baranowski [16] demonstrates that even a single spraying of the substrate under horse-chestnut trees significantly reduces the number of infected leaves and delays leaf-fall. The analysis of horse-chestnuts watered with ProAgro 100 SL (Imidacloprid) in the experimental field showed that the treatment significantly limited the occurrence of C. ohridella (Fig. 1a, b). In the treatment year, only a slight percentage of leaf damage was noted in the lower crown part where the infection degree by the leaf miner is usually higher (Fig. 1a, b). Horse chestnuts treated with ProAgro 100 SL kept their foliage for a longer period, by 3 4 weeks on average, than control trees. The agent reduced caterpillar predation, especially of the second generation of miners, on average by % in the upper tree part and % in the lower part of the crown in comparison with the control (Fig. 1a, b). The agent s beneficial effect was also observed in trees with a smaller diameter at breast height (ca. 700 mm). However, only single mines that did not occupy more than 10 % of the leaf surface towards the end of the vegetative season were observed as early as in the second year after soil application. Tree damage was in this period smaller by 10 % on average than that recorded on horse-chestnuts treated with microinjections (ca. 20 % leaf infestation by C. ohridella). The present observations show that both microinjections and the soil application method similarly reduce the occurrence of the horse-chestnut leaf miner (even up to 90 % in comparison with control trees in late summer) (Fig. 1a, b). Therefore, soil application of a chemical agent can be an alternative to microinjections as a non-invasive method.

5 Effectiveness of Chemical Control of the Horse-Chestnut Leaf Miner Conclusions 1. Microinjections did not successfully reduce horse-chestnut leaf miner predation in the treatment year. One hundred percent effectiveness was not observed in the two years after the treatment. Moreover, pathogenic symptoms caused by Guingardia aesculi and distinct post-drilling, unhealed wounds in trunks were recorded. 2. The effectiveness of soil application of the Imidacloprid agent used to control the horse-chestnut leaf miner was comparable with that of microinjections. Therefore, soil application may become an alternative method in pest protection of trees. Its non-invasiveness is also an additional advantage. Refereneces [1] Kloudová K., Mertelík J. and Vanc P.: [in:] Proc. Conf. Plant protection in the III millenium, Ivanka pøi Dunaji, 2002, [2] abanowski G.: Ochr. Roœl., 2004, 4, [3] Baranowski T. and Potocka E.: Streszczenia XLVII Sesji Naukowej IOR, Poznañ luty 2007, 280. [4] Pavan F., Barro P., Bernardinelli I., Gambon N. and Zandigiacomo P.: J. Arboric. 2003, 29(5), [5] Malinowski H.: Sylwan, 2006, 1, [6] abanowski G. and Soika G.: Progr. Plant Protect./ Post. Ochr. Roœl., 2001, 40(1), [7] Gilbert M. and Gregoire J.-C.: J. Appl. Entomol., 2003, 127, [8] Lethmayer C.: [in:] Plant Protection and Plant Health in Europe: Introduction and Spread of Invasive Species. 2005, BCPC Symposium Proceedings no. (81), [9] abanowski G. and Soika G.: Materia³y II konferencji w Ogrodzie Botanicznym UJ w Krakowie, 2004, [10] Baranowski T.: Ochr. Roœl., 2002, 11 12, 6 7. [11] Dziegielewska M., Kaup G. and Adamska I.: Progr. Plant Protect./ Post. Ochr. Roœl., 2005, 45(2), [12] abanowski G. and Soika G.: [in:] Bioró norodnoœæ i ekologia populacji zwierzêcych w œrodowiskach zurbanizowanych, Bydgoszcz 2001, [13] Soika G. and abanowski G.: Progr. Plant Protect./ Post. Ochr. Roœl., 2005, 45(2), [14] Webb R.E., Frank J.R. and Raupp M.J.: J. Arboric., 2003, 29(5), [15] Lohrer T., Gerlach W.W.P., Fischer P., Fischbischler P. and Einchinger K.M.: Nachricht. Deutschen pflanzenschutz, 2003, 55(10), [16] Baranowski T.: Materia³y II konferencji w Ogrodzie Botanicznym UJ w Krakowie, 2004, SKUTECZNOŒÆ CHEMICZNEGO ZWALCZANIA SZROTÓWKA KASZTANOWCOWIACZKA INSEKTYCYDAMI Z GRUPY INHIBITORÓW BIOSYNTEZY CHITYNY METOD DOGLEBOWEJ APLIKACJI I MIKROINIEKCJI Streszczenie Wœród najskuteczniejszych metod zwalczania szrotówka wymieniane s¹ mikroiniekcje oraz opryskiwanie drzew preparatami z grupy zwi¹zków acylomocznikowych. W przeprowadzonych badaniach porównywano skutecznoœæ zwalczania szrotówka kasztanowcowiaczka insektycydami z grupy inhibitorów biosyntezy chityny (sk³adnik czynny imidachlopryd) metod¹ doglebowej aplikacji lub przez iniekcje preparatu bezpoœrednio do pnia drzewa. Obserwacje prowadzono w latach w wybranych zieleñcach Szczecina. Na podstawie przeprowadzonych badañ stwierdzono zró nicowany stopieñ pora enia drzew przez szrotówka poddanych mikroiniekcji, uzale niony od ich wieku. Stopieñ tego pora enia nie przekracza³ 30 % u drzew starszych (œrednica pnia ok mm) i 15 % u drzew m³odszych (œrednica pnia ok. 700 mm). Tymczasem

6 258 Magdalena Dziêgielewska and Gra yna Kaup kasztanowce podlane na poletku doœwiadczalnym insektycydem ProAgro 100 SL (imidachlopryd) wykaza³y pozytywn¹ reakcjê na wykonany zabieg. W dolnej czêœci korony drzew, gdzie z regu³y stwierdza siê wy szy stopieñ pora enia liœci przez szrotówka, zaobserwowano zaledwie niewielki procent ich uszkodzenia (do 15 % w pierwszym roku obserwacji). Z uzyskanych danych wynika, e doglebowa aplikacja preparatu chemicznego mo e byæ metod¹ alternatywn¹ do zabiegów opryskiwania i mikroiniekcji. S³owa kluczowe: Cameraria ohridella, Aesculus hippocastanum L., mikroiniekcje, aplikacja doglebowa, ProAgro 100 SL