Needlecast diseases of evergreens are caused by many different fungi. Little is known about when these fungi can attack a tree, how long the fungus must be in the tree before needles are shed, when is the best time to apply a fungicide to protect the needles, or which chemical provides the best protection. However, progress is being made in these areas.

Needles infected with fungi generally fall several months after the actual period of infection. The period of greatest infection for most needlecast fungi is during the late spring and early summer months. Symptoms, the visible indications that the needle is diseased, do not appear until the late winter, spring, and early summer of the next year.

All the fungi that cause needlecasting form small structures on the infected needle in which thousands of spores form. These "fruiting structures" may be black, orange-red, or tan, depending upon the fungus. Fungi that grow on dead or dying needles but do not cause needlecasting may form similar structures. Finding a fungal fruiting structure on a dead needle is not proof that the tree has a needlecast disease. The accurate identification of the fungus requires training, skill, and experience and must be done to be certain the tree has a fungus-caused needlecast disease.

Managing Needlecast Diseases

Needlecast fungi require abundant moisture for their growth and development. Plant so that the air circulation around trees will be good. Avoid establishing dense plantings. Maintain good weed control so that weed growth does not impede air circulation around the lower branches. Avoid planting susceptible trees in low areas or shady areas where humidity and needle wetness tends to be high for prolonged periods. Fungicides can be applied to protect healthy foliage. Note that in order to legally use a fungicide on a tree, the name of the tree must appear on the fungicide product label.

Douglas Fir Needlecasts
Pine Needlecasts
Pine Needle Blights
Rhizosphaera Needlecast on Spruce

DOUGLAS FIR NEEDLECASTS
	Rhabdocline Needlecast	Swiss Needlecast
Fungus	Rhabdocline pseudotsugae and R. weirii	Phaeocryptopus gaumannii
Infection period	Mid-May through June	May-June
Symptoms	May-June of the year following infection, yellow spots form on the previous years needles. Spots become reddish brown.	March-May of the year following infection or April-June two years after infection, needles gradually turn brown and fall, leaving only the current years needles
Sporulation	May-June orange-red fruiting structures form in the spots. These are easily seen when wet.	May-June a row of tiny black dot shaped fruiting structures form on either side of the needle midrib on the underside of the needle. A magnifying glass is needed to see the individual structures.
Favorable environment	Free moisture on needles. Cool temps. = 53-59 degrees F.	Free moisture on the needles
Management	1. Plan plant placement and weed control to insure good air circulation to reduce humidity and period of needle wetness.	1. Plan plant placement and weed control to insure good air circulation to reduce humidity and period of needle wetness.
	2. Three or four applications of chlorothalonil or mancozeb: 1st as first buds break, 2nd one week later, 3rd three weeks after first buds break, 4th if spring is prolonged by cool weather, 6 weeks after first bud break.	2. Two applications of mancozeb or chlorothalonil, 1st when new shoots are 1 1/2 inches long, 2nd three weeks later.

PINE NEEDLECASTS
	Ploioderma	Lophodermium	Cyclaneusma
Fungus	Ploioderma lethale	Lophodermium seditiosum	Cyclaneusma minus
Hosts	Hard pines, especially red and Austrian	Most pines including Scots and Austrian	Scots and Austrian
Infection	May-June	Mid-July-mid-September	Primarily April-June but also April-December when temps are above freezing and free moisture is on the needles.
Symptoms	March-May the year after infection. Red-brown spots develop on needles. Tips of needles girdled by spots die while needle base remains green and needle remains attached to twig. Needles are cast in May-June.	March-May the entire needle browns and is cast May-June.	Mid-September-December the year after infection or April-June 2 years after infection yellowing needles develop distinct brown bars.(Yellow needles are also caused by two-spotted pine aphid feeding.)
Sporulation	May-June black structures on the dead part of the needle open via a long slit to release spores.	Mid-July to mid-Sept. black football-shaped structures on the cast needle open via a long slit and release spores.	April-December white to tan round structures fill the brown bars on the infected needle and open wide to release spores.
Favorable environment	Free moisture on needle is favorable for all three pine needlecasts.
Management	1. Plant placement and weed control to insure low humidity and short periods of needle wetness.	1. Plant placement and weed control to insure low humidity and short periods of needle wetness.	1. Plant placement and weed control to insure low humidity and short periods of needle wetness.
	2. Apply chlorothalonil three times at 3 week intervals beginning late May.	2. Apply chlorothalonil, or chlorothalonil + triadimefon or mancozeb three times. 1st mid-July If early summer is warmer than normal start mid-June. 2nd and 3rd at 3 week intervals.	2. Apply chlorothanonil or chlorothalonil + triadimefon 1st mid-March 2nd early May 3rd mid-June 4th mid-August 5th mid-October

PINE NEEDLE BLIGHTS
	Redband	Brown Spot
Fungus	Dothistroma pini	Scirrhia acicola
Hosts	Austrian, ponderosa, and most other pines but not Scots or red.	All pines.
Infection period	May to October	Primarily June-July but also anytime during the growing season.
Symptoms	Infected needles are mottled and have dark green bands and yellow to tan spots. Mottled areas turn brown to red-brown in color. Needle tips may die while bases remain green. Needles may be cast the autumn after infection or remain attached until the following spring and summer.	Same as for redband.
Sporulation	May-October, spores are blown or splashed from tiny dark brown or black fruiting structures that can be observed with a magnifying glass to lack the longitudinal slit opening characteristic of needlecast fungi.	Same as for redband. Distinguishing this from redband requires a microscopic examination of spores.
Favorable environment	Wet foliage	Wet foliage
Management	1. Control weeds and select a planting site so that needles will not remain wet for extended periods. 2. Apply copper once in mid-May and again in mid-July to protect current year needles. CAUTION: Copper can be phytotoxic. Follow the label carefully.	1. Same as for Redband. 2. Apply chlorothalonil or mancozeb when needles are half elongated and again 3 weeks later.

RHIZOSPHAERA NEEDLECAST ON SPRUCE
Fungus	Rhizosphaera
Hosts	Spruce, especially Colorado blue spruce
Infection period	May-June and September-October
Symptoms	Several months after infection, needles turn lavender in color. Tiny black fruiting structures form in rows on either side of the midvein on the underside of the needle. Large patches of needless areas develop on the tree.
Sporulation	May and September
Favorable environment	Free moisture on the needles.
Management	Make two applications of chlorothalonil. The first is made when new shoots are 1 1/2 inches long and the second 3 weeks later.

Fungicides mentioned above:

CHEMICAL NAME	TRADE NAME
chlorothalonil	Bravo
copper	TennCop 5E, Bordeaux, Camelot, Basicop
mancozeb	Dithane
myclobutanil	Nova, Eagle, Systhane
triadimefon	Bayleton