In Kansas, the symptoms for pine wilt usually appear from August through December. In general, the trees wilt and die rapidly within a short period of time. Occasionally, trees may survive for more than one year. The early stages of the disease are subtle and may vary. Three to four weeks following infestation by the pinewood nematode, transpiration of the foliage decreases and resin production is reduced.
Needles initially show a light grayish-green discoloration, then turn yellow and brown.
The disease may progress uniformly through a tree or branch by branch, depending upon the size of the tree and the environmental conditions during the growing season. The needles remain attached for up to six to twelve months after the tree has died. The rapid death of a tree contrasts with other pine problems such as fungal diseases, insects, or environmental stresses. In addition to rapid wilting and yellowing of the foliage, another important symptom is reduced resin production. Branches and twigs become brittle and dry and will break easily.