Diseases caused by these fungi are generally more serious in bareroot nurseries than in greenhouse container nurseries, where contamination of growing media, temperature, and irrigation are controlled more easily. However these fungi can become a problem if growing media become contaminated or a pathogen is introduced on seeds or in irrigation water. These fungi are able to survive for various periods as resting spores or mycelium in soil and residual host tissues, and they can be seedborne. They also can persist in styroblocks.

Seedlings are infected when favorable soil moisture and temperature conditions and seed or root exudates are present. Fusarium species may be seedborne and can cause pre- and postemergence damping-off as well as hypocotyl rot and root rot later in the growing season. Fusarium primarily affects 1+0 seedlings, while Phytophthora affects 1+0 and 2+0 seedlings; symptoms are most apparent in 2+0 seedlings.

The practice of tilling in "green manure" cover crops can aggravate disease problems by providing high levels of organic matter that result in increased pathogen levels. A bare fallow rotation instead of cover crop can significantly reduce pathogens and improve fumigation efficacy.

Phytophthora root rot in 1+0 seedlings show as reddish brown discolored roots. Aboveground symptoms occur in the spring of the second year and include patchy chlorosis, browning, and mortality in low, poorly drained beds. Roots initially are discolored and eventually rot off completely. A characteristic dark brown stain in the root cambium, often with a distinct margin between healthy tissue above and diseased tissue below, is diagnostic.

Pythium-infected seedlings have stem tissue that separates around the root collar where the epidermis sloughes away from the inner xylem. Fusarium-infected seedlings undergo a softening of the root collar tissue, and the trees fall over without separation of the stem tissues.

1. Avoid poorly drained soil.
2. Use properly conditioned seeds.
3. Rotate planting beds with nonsusceptible hosts such as small grains to reduce fungal inoculum levels. Avoid legume cover crops. Keeping beds weed free and fallow with periodic tilling during interrotational seasons is even better.
4. Do not reuse planting containers or thoroughly wash and disinfect them if they are reused. Sanitizing styroblocks by heat, fungicide, or biocide treatment helps control disease problems. Discard older styroblocks because after multiple uses sanitation efficacy is reduced.
5. Use well water or filter and/or decontaminate surface water used for irrigation. Irrigate only enough to thoroughly wet the root zone. Water as needed based on water use of the seedlings.
6. Plant when soil temperature is warm enough to promote rapid germination and emergence.
7. Soil pH of between 5.2 and 5.7 is ideal for most Pacific Northwest conifers.

1. Preplant fumigation is the most commonly used control in conifer nurseries, but cultural practices can reduce the need to fumigate.
   1. Basamid; see label. 24-hr reentry plus ventilation.
   2. Methyl bromide. Restricted-use pesticide.
   3. Telone II. Rates are based on planting depth and soil type. See label for details. 5-day reentry. Restricted-use pesticide.
   4. Telone C-17. Rates are based on planting depth and soil type. See label for details. 5-day reentry. Restricted-use pesticide.
2. Seed treatment is not recommended, as it has not been very successful.
3. Postplant fungicides for Pythium. Rotate fungicides that have a different mode of action for resistant management.
   1. Alude at 1 to 2 qt/100 gal water applied as a soil drench at a rate of 1gal solution/sq yd. Follow application with irrigation. Can also be used as a foliar spray at 14- to 21-day intervals. 4-hr reentry.
   2. Banrot 40 WP at 6 to 12 oz /100 gal water. 12-hr reentry.
   3. Fosphite at 1 to 2 quarts/100 gal water. Do not use copper products within 20 days of treatment and do not use spray adjuvants. 4-hr reentry.
   4. Mefenoxam 2 EC at 1.25 pints/A as a broadcast spray over beds in at least 50 gal water at seeding or transplanting. Use at 2.5 pints/A as a broadcast spray for newly transplanted 2-year-old seedlings. Do not use as a curative treatment. 48-hr reentry.
   5. Subdue MAXX at 1.25 pints/A as a broadcast spray over beds in at least 50 gal water at seeding or transplanting. Use at 2.5 pints/A as a broadcast spray for newly transplanted 2-year-old seedlings. Do not use as a curative treatment. Zero-hr reentry.
   6. Terrazole 35 WP at 3.5 to 10 oz/100 gal water as a soil drench only at time of seeding or transplanting. 12-hr reentry.

James, R.L., R.K. Dumroese, and D.L. Wenny. 1988. Occurrence and persistence of Fusarium within styroblock and ray leach containers. In: Landis, T.D., ed. Proceedings: Combined meetings of the western forest nursery associations. USDA Forest Service General Technical Report RM-167. Fort Collins, CO.