– – – Austrian pine, Ponderosa pine – – –
Infection occurs from spring into autumn. Translucent slightly swollen spots appear on Old Needles. The centers turn yellow to brown and may later join slightly banding. The needle tips beyond the lesion die. After winter, small black spores break through the needle surface. Symptoms appear that autumn or the following summer. Disease progresses the bottom up to the crown of the tree.
Diplodia Tip Blight
– – – Austrian pine, Ponderosa pine, Scotch pine, Red pine – – –
Infection occurs during the three weeks of new growth when shoots and needles elongate. Lesions may exude small drop of resin. Lesions enlarge quickly and stop growth before complete elongation. New needles, dying in May or June, turn yellow-green then straw color. Tissue becomes resin soaked and dark brown. Resin will crystallize and flake. Dark spores push through needles in late summer and next spring. Disease progression from bottom up to crown. There is no banding.
– – – Austrian pine, Ponderosa pine, Scotch pine, Red pine, White pine – – –
Infection occurs mostly in June and July on succulent tissue. Older needles show straw yellow spots, becoming light brown with a dark border towards autumn. Lesions are sunken spots because green tissue shrinks as needle dies. Second type of lesion is a brown spot with amber yellow banding. Diseased needles often have dead tips with several zones of green tissue between bands and green bases. Dark spores show the following year in late spring. Disease confined mostly to bottom of tree.
Lophodermium Needle Cast
– – – Austrian pine, Scotch pine, Red pine – – –
Infection occurs in August and September on current year’s growth. Symptoms appear the following April thru June as dramatic browning partially hidden by new foliage. These, now older needles, show irregular brown spots or raised spots with banding. Dead needles turn from reddish brown to straw and fall off in June or July. The disease is usually on lower branches but can be uniform from bottom to crown.
Rhizosphaera Needle Cast
– – – Blue Spruce – – –
Infection occurs mostly from May to June on new succulent growth or on older stressed needles. Symptoms arise in late summer as yellow mottling of 1st year needles which soon turn brown to purplish brown. Browning continues during late winter and early spring. Infected needles, showing black spores, fall off from summer into the autumn. The disease is usually confined to the bottom but can progress towards the crown.
Always use Spreader Sticker with fungicide spray to increase its effectiveness.
Diseases usually infect stressed trees, so proper cultural care such as Fertilizing, Watering, and Mulching goes a long way in prevention. Good care costs a lot less than spraying with fungicides.