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Chrysomyxa weirii, is a fungus that causes a disease, commonly known as Weir's cushion rust, of spruce trees. It is mostly a cosmetic problem, causing yellowish spotting and banding on spruce needles, but in some cases can cause severe premature defoliation. [1]
Many pine trees turn yellow this time of year because of normal “needle drop” on the inside branches
Picea abies, the Norway spruce [2] or European spruce, [3] is a species of spruce native to Northern, Central and Eastern Europe. [ 4 ] It has branchlets that typically hang downwards, and the largest cones of any spruce , 9–17 cm long.
The yellow-headed spruce sawfly, Pikonema alaskensis, is widely known in the northern United States and Canada as a destructive pest of spruce. [1] It attacks white, black, Norway, and Colorado blue spruces. The larvae at first prefer new foliage, but after becoming about half-grown, old needles are included in their diet too.
Needles turn yellow or brown or drop off completely most often due to improper watering (too much or too little), drafts, or low light. You can trim off the brown branches with pruners, but be ...
The symptoms give the disease its name. The first signs of infection that can be seen are yellow and brown spots that develop on the living needles, [7] [8] which soon turn red. This infection starts on the base of the crown on older needles, which then turn a brownish red at the tip, while the rest of the needle remains green. [9]
The peg-like base of the needles, or pulvinus, in Norway spruce (Picea abies) Pulvini remain after the needles fall (white spruce, Picea glauca) Determining that a tree is a spruce is not difficult; evergreen needles that are more or less quadrangled, and especially the pulvinus, give it away. Beyond that, determination can become more difficult.
The plant pathogenic fungus Leucostoma kunzei (formerly Valsa kunzei) is the causal agent of Leucostoma canker (also known as Cytospora canker or spruce canker), a disease of spruce trees found in the Northern Hemisphere, predominantly on Norway spruce (Picea abies) and Colorado blue spruce (Picea pungens).