8.2 Diseases - Time for Concern

8.2.1 BLOOM

8.2.1.1 Powdery Mildew

Symptoms- Powdery mildew overwinters on elderberry twigs. Infection is evidenced by white powdery patches of mycelium and spores that appear on the leaves in early spring. As time passes, these patches may turn rusty brown. Infected leaves may drop prematurely during hot weather. Heavily infected plants may be compromised by powdery mildew

Management Options

Guideline

Scouting/thresholds

None established.

Resistant cultivars

None established.

Cultural management

Prune plants to improve air circulation.

Conventional products

Sprays are only necessary during humid or wet weather in the spring. In plantings where disease historically occurs, apply the first application before typical time of disease onset.

A.    azoxystrobin - Abound 2.08F (10 fl oz. /A). Apply beginning at bloom and repeat at 7-14 day intervals.

B.    propiconazole - Orbit (6 fl oz. /A) or Tilt (6 fl oz/A). Apply at 5-10% and repeat on a 14-day schedule during favorable conditions.

Organic products

(May also be used in conventional production.)

A.    potassium bicarbonate –Kailgreen 2.5 – 3.0 lb/A). Do not mix with highly acidic products or nutrients.

8.2.2 SPECIAL PESTS

Symptoms- This disease may overwinter infected plant material or as survival structures (sclerotia) within the soil. Weeds may serve as additional hosts for Verticillium inoculum. Shoots of infected bushes will wilt and dieback beginning at the tips. Entire bushes may die as the wilt progresses.

Management Options

Guideline

Resistant cultivars

None established.

Cultural management

A.   Many weeds are hosts of the Verticillium fungus. Weeds should be strictly controlled in planting sites to keep the Verticillium populations low.

B.   Replant in a new location previously not planted to raspberries, strawberries, potatoes, tomatoes, or eggplants, and, to a lesser extent, squash, cucumber, pepper, and melon.

Conventional and

Organic products

A.    Streptomyces lydicus WYEC108- Actinovate AG (2-12 oz/A). Since Actinovate AG contains live spores of a microbe, best results will be obtained if used prior to disease onset.