Ploioderma Needle Cast

Although Ploioderma needle cast occurs in spring, symptoms are not apparent until winter when yellow spots and bands appear, giving the needles a mottled appearance.
Ploioderma Needle Cast - Articles

Updated: November 21, 2017

Ploioderma Needle Cast

Symptoms of needles infected with Ploioderma needle cast. Courtesy of Tracey Olson, PDA

Ploioderma lethale (Dearn.) Darker

Hosts

  • Austrian and red pines
  • Other two- or three-needled, hard-pine species

Damage Potential

  • Low–moderate

Symptoms and Signs

  • May first develop in needles on lower branches

Late Winter Through Early Spring

  • Infected needles develop reddish-brown spots
  • Spots may girdle needle and kill tips, leaving healthy, green base
  • Current season’s infected needles redden by early spring

Late Spring Through Early Summer

  • In June, fruiting bodies may develop within spots and dead portion of needle; fruiting bodies appear as long (2⁄125–1⁄5 inch; 0.4–5.0 mm), black lines
  • Dead tips of infected needles with green bases may break off
  • Completely infected needles are cast

Causes of Similar Symptoms

  • Other needle cast diseases, especially Lophodermium needle cast

Identification

Ploioderma needle cast is a disease of hard pines. Although the infection occurs in spring, symptoms are not apparent until winter when yellow spots and bands appear, giving the needles a mottled appearance. During the following spring, the spots and bands girdle the needle, turning the tip straw brown or gray in color while the base of the needle remains green. Black, longitudinal fruiting bodies appear in the infected portion of the needles in June. Sporulation occurs after they mature, and the needles are cast to the ground by the end of summer.

Ploioderma needle cast closely resembles Lophodermium needle cast in symptoms and disease cycle. However, Lophodermium fruiting bodies are elliptical to round, while those of Ploioderma are elongate, running longitudinally on the needle.

Biology and Life Cycle

During wet spring and early summer weather, colorless spores are released from fruiting bodies that have opened lengthwise on the needle (Figure 1). Spores can be disseminated by wind or rain and will germinate on newly emerging needles close by. The fungus enters the needle through the stomata and the first symptoms of infection are visible on the new growth by winter (Figure 2). The next spring, fruiting bodies release spores and the process begins again.

Figure 1. Infected needles with characteristic elongate, black fruiting bodies. Courtesy of Tracey Olson, PDA

Figure 2. Early infection of Ploioderma needle cast. Courtesy of Joseph O’Brien, USDA Forest Service, Bugwood.org (#5057098)

Disease Cycle Calendar (Single Year’s Growth of Needles)

Monitoring and Management Strategies

Plantation Establishment

  • Choose a site that will promote drying of trees (southern slope, good drainage, nonshaded).
  • Plant resistant varieties suited for the environmental conditions.
  • Inspect nursery stock before buying and planting.
  • Adequately space trees to ensure air circulation and reduce moisture levels.

Preseason

  • Maintain good weed control.
  • Scout needles in early spring for signs and symptoms of Ploioderma.

Growing Season

  • If Ploioderma is found in the plantation, consider treating with a fungicide in the spring during bud break.
  • At the end of the season, evaluate results and update records.

Control Options

Biological

  • No recommendations are available at this time.

Mechanical

  • Promptly remove and destroy branches and trees showing signs of Ploioderma.

Biorational

  • No recommendations are available at this time.

Chemical

  • To protect new growth in the spring, apply a fungicide when new growth is 2 inches long and needles are just beginning to emerge from the fascicles.
  • Two additional fungicide applications may be necessary at 14- to 21-day intervals to protect needles during the spore release and infection period.

Next Crop/Prevention

  • Purchase and plant disease-free nursery stock from a reputable company.