Oaks tolerate both drought and heat. "Ideal in times of climate change", according to forestry director michael kreppel, if it weren’t for the gypsy moth, a butterfly species whose caterpillars threaten to strip almost 160 hectares of deciduous forest bare.
The area affected is 85 hectares near seigendorf in the municipality of hirschaid, and 50 hectares in the "lohe" near bammersdorf, 16 hectares in trailsdorf, on the border to seubling and eight hectares in the municipality of igensdorf. In these areas, which cover a total area of almost 230 soccer fields, the pest was already active last summer.
In two days everything was bare
Forest owner georg hubert from eggolsheim, who enjoyed the lush green of his woods last spring, described the situation as follows: "when i looked into the woods from the road on christmas eve, it looked as if someone had switched on neon lights there. The young shoots of the beech trees of the undergrowth were completely eaten bare. Even the grass on the forest floor had disappeared." Two days later, the foliage of the treetops had also fallen victim to the caterpillars. The gypsy moth does not even like anything left over from the second shoots of the trees in the year.
Now the trees in the affected forests are full of spores with thousands of eggs in which tiny caterpillars are waiting to hatch out. The females laid their eggs in the lower part of the trunk and in the moss, in the crowns it was obviously too hot for them, analyzes michael kreppel.
An incredible number of spiders
And there are an incredible number of spins. The forester responsible for eggolsheim and trailsdorf, matthias jessen, found up to ten such nests on the lower two meters of the trees when he examined them. Whereas last year there were two nesting sites per tree, the statistical average in the lohe area is now 5.3. In igensdorf and seigendorf the situation is no better.
Forester stefan ludwig and forest ranger stefan muller confirm this trend. There is a need for action, because the natural enemies are overwhelmed with the explosive reproduction of the gypsy moth. Hannes lemme from the state institute for forestry, who had traveled from freising, confirmed that the spores were increasingly being attacked by viruses or caterpillars. However, no one could predict whether and how quickly these natural enemies would be able to reduce the population of the sponge moth to a normal level. For this reason he advised the use of the pesticide mimic. This is a liquid spray that is successfully used in fruit growing. The preparation acts as a skin accelerator and is harmless to ladybirds, spiders and ichneumons, predatory mites and bugs. It is also not suspected of being carcinogenic or gene-damaging.
Everyone must agree
The product is to be applied at a concentration of 0.04 percent by helicopter over the affected areas. So three quarters of a liter of mimjc is enough for one hectare of oak forest. Each owner decides for himself whether the forest is to be sprayed. Nearly 180 forest owners in the counties of forchheim and bamberg were therefore contacted by the agricultural office.
Subject to approval, the fight against the pest is expected to begin in early may. The distance from the edge of the forest and from the water must be 25 meters. The minimum distance to buildings and roads is 50 meters.