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120th & Maple, Omaha, NE

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Common Evergreen Diseases & Insects

Common Evergreen Diseases

Diplodia Tip Blight of Pine
The Diplodia fungus causes death to the needles starting at the tip on Austrian, Scotch, Ponderosa and Mugho Pine. It appears as dead branches scattered through the plant often starting at the bottom of the plant.

Older plants (25-30 years) are most often affected. If the infection remains untreated, it may kill the entire branch. Ultimately, the whole plant may become infected and consequently die. Infected branches should be pruned off and all the needles and cones beneath the tree should be removed as these harbor the pathogens during the winter. Diplodia Tip Blight can be confused with damage to shoots caused by Pine Tip Moths. However, moth damage may be recognized by the presence of larvae or by tunnels within the affected part of the shoot. Diplodia can be controlled by applying the proper fungicide twice, approximately between April 24th and May 8th at one to two week intervals. Fungicides applied after mid-May are ineffective. A wet cool spring will often result in a higher incidence of fungus spore development. Yearly applications of fungicides are necessary!

Dothistroma Needle Blight of Pines
Dothistroma is the most common fungal disease of pines. It affects Austrian, Ponderosa, Mugho, and Scotch Pines. The infection usually shows up on current year or older needles during the fall, appearing as small yellow to tan spots (fruiting bodies) on the needles. Spores are released during periods of rain from May through October. The needle first dies from the spot to the base of the needle. Once the needle dies, it will drop off, usually in late spring or early summer of the year following infection. The older needles will be the first to drop. (Old needles will drop off when they reach the end of their life spans; but this normal needle drop occurs in late summer, not early summer.) Infection is usually more severe on lower branches, but can occur over the entire tree. If the disease continues untreated, it can kill all but the new growth, reducing the vigor and appearance of the plant. Fungicide should be applied in mid-May and repeated through mid to late June.

Common Evergreen Insects

Pine Needle Scale
This scale can seriously damage pine and spruce and may injure fir and junipers. Eggs hatch in late spring (May) and the young crawlers feed by inserting their mouth parts into needles. When heavily infested, the foliage may appear completely white. The insects can be scraped or picked off. The underside of the scale is usually soft and white in color. Affected needles turn brown and drop. Repeated infestations, if left untreated, may kill young trees or weaken older trees. A parafinic oil spray may be used prior to new candle growth, in March. The oil will suffocate some of the over-wintering eggs. Apply insect control following these average dates. In mid May and again about 10 days later. Repeat in mid June and again the first week of July.

Pine Tip Moth
Eggs are laid on buds or needles near tips. Eggs hatch in about seven days. Young larvae feed for a time on the needles, then bore into the buds and shoots. Damaged buds often have resin accumulation on the sides of their tips. This destroys the internal tissue, and the damaged tips turn brown and crumble when rubbed between the fingers. Apply insect control following these average dates. Spray to thoroughly drench needles. Two applications should be made, the first during the third week of May, the second during the first week of July.

Zimmerman Pine Moth
The Zimmerman Pine Moth has become a threat to pine trees in recent years. During it's larval stage it usually tunnels into the trunk near a branch. This weakens the branch possibly causing it to eventually die and snap off. A distinguishing feature of larval damage is the presence of sap oozing from the point of entry. This sap will form large, crusty, whitish masses on the trunk. Apply insect control following these average dates, April 7-15th, and again between August 7-15th. Systemic Implants can be used and should be applied once in mid April. Do not use implants on trees with trunks under 4 inches in diameter.

Mites
Mites are microscopic spider-like pests, which suck sap out of their host plants. A wide range of plants is affected and some types of mites are host specific, meaning they attack only a certain type of plant. Damage from mites can range from yellow stippling of the foliage to complete browning and death of infested foliage. Fine webs are often present during mite infestations. You can test for the presence of mites by holding a white piece of paper under a branch and tapping firmly on the branch. Small specks may be detected moving on the paper. Mites can occur during any part of the growing season but prefer hot and dry conditions. Spray for mites with an insect control whenever infestations occur. Damage may be minimized by spraying in April or May and repeating every ten to fourteen days as needed.

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