Symptoms on needles: dull green color of needles (not any more shining), fine dark mottling, slight yellowing or browning (for instance species of Nalepella on fir needles, species of Phyllocoptes on spruces); symptoms on buds: buds remain closed, abnormal branching (abnormal development of additional buds); symptoms on twigs: dieback, small knot-like galls, loss of needles (for instance species of Trisetacus on pines). Needle symptoms can easily be mistaken for symptoms caused by spinning mites, abnormal bud production for fungal diseases and herbicide damage, and galls on the twigs for fungal diseases or galls of insects.
Affected tree species
Fir; Pine; Spruce;
Gall mites are hardly endangering conifers. Damage is mostly limited to needle losses or slight shoot dieback. In Christmas tree production, damage can cause economic losses, especially, since monocultures favour mass development of the mites.
Curative measures Only in economic plant production and only in cases of heavy infestations a chemical control by acaricides before budburst is recommended (see Federal Register of Plant Protection).
Gall mite (Nalepella sp.)
eggs and exuvia (white, elongate) of free living spruce gall mites (Phyllocoptes)
distorted needles of Norway spruce with numerous gall mites (Phyllocoptes )
Phyllocoptes sp., larva
gall mite (Nalepella) on a fir needle
browning of a Nordman's fir needle caused by free living gall mites Nalepella sp.