|
Résumé :
|
This review is based mainly on the answers to three quetionnaires send in 1965 to 309 personns throughout the country (Table 1). In addition, samples received from growers, telephone reports and observations made by the personnel of the department were also taken into consideration. The spring and early summer were very dry. The numbers of insect pests in the early part of the growing season were rather normal, but damage in many places was great, since the prolonged drought reduce the resistance of the crops. In mid-summer, low temperatures and repeated rains checked the increase of many insects species. At the end of August there was a warm period, but it no longer was able to appreciably affect the abundance of crop pests. The incidence of pests and the damage caused by them can be regarded, on the whole, as quite normal (Table 1). Striking exceptions to this were the apple fruit moth (Argyresthia conjugella) and Lygus bugs (Lygus spp., especially Lygus rugulipennis), wich caused damage equalling or exceeding that of the most epidemic years. Similarly, the rosy rustic moth (Hydroecia micacea) aroused concern among farmers, since its larvae more common and numerous than ever before. Lygus bugs were a serious nuisance in sugar beets (Figs. 1, 2). Because of the excessively large numbers of these bugs, the only effective control would have been sprayings at intervals of one or two days. According to the questionnaires, the apple fruit moth exceptionnaly plentiful, causing damage to 47 % of the apples (Figs. 3, 4). Owing to the cool and rainy weather, their period of oviposition began later than normal and was prolonged over a long time. Consequently, sprayings performed at the usual time gave only poor control of these pests. Reports of damage by larvae of the rosy rustic moth were received in 65 cases of potato, 54 of sugar beet, 19 rhubarb, 19 strawberry, and 1-2 cases each of light other crops. Destruction caused to rhubarb occured as far north as 67 degrees N lat. (Figs. 5, 6). The potato root eelworm (Heterodera rostochiensis) was encountered in four new localities. Control of this pest is now a simple matter, since a resistant potato variety, Antinema, is presently available in this country. The English grain aphid (Macrosiphum avenae), which was very numerous int he previous year, occured only in small numbers in 1965. Reports of a total of 162 pest species were received in this year. According to Vappula (1965, Ann. Fenn. 1, suppl. 1, 239 pp.) 1084 pest species occur in Finland. At the end of 1965 this number had risen to 1086.
|
