Crown Rot (Fusarium spp.)
Vigorously growing plants are less susceptible to crown rot. Buy top quality crowns. Use new land or land where asparagus has not been grown for 10 years. Use tolerant varieties.
Rust (Puccinia asparagi)
Asparagus rust attacks fern foliage and can spread rapidly, affecting production in subsequent years. Fern residues should be removed and destroyed prior to spear emergence in the spring. Control volunteer asparagus plants that might be infected. Resistant cultivars are not available. Apply fungicides after spear harvest is complete.
FRAC Group 3:
myclobutanil (Rally 40 WSP): 5 oz/A; PHI 180d, REI 24h. Begin applications after spears have been harvested. Observe a 30-day plant-back interval between the last application and planting new crops at the treatment site.
tebuconazole (Monsoon): 4 to 6 fl oz/A; PHI 180d, REI 12h. Begin applications after spears have been harvested. Do not make more than 3 foliar applications per year.
FRAC Group 11:
mancozeb + azoxystrobin (Dexter Max): 2 to 2.2 lb/A; PHI 180d, REI 24h, Groups M03 & 11. Begin applications after spears have been harvested. Rotate with a non-Group 11 fungicide.
FRAC Group BM01:
thyme oil (Guarda): 1 gal/29–159 gal water (0.625%–3.3% v/v); PHI 0d, REI 0h.
FRAC Group BM02:
Bacillus amyloliquefaciens strain D747 (DoubleNickel 55OG): 0.25 to 3 lb/A; PHI 0d, REI 4h.
FRAC Group M01:
copper (Badge SC): 1 to 2.5 pt/A; PHI 0d, REI 48h. Disease suppression only. Tank mix with other products labeled for rust control. Addition of sticker/spreader recommended.
FRAC Group M02:
sulfur (Microthiol DisperssOG): 10 to 30 lb/A; PHI 0d, REI 24h. Apply to ferns after cutting.
FRAC Group M03:
mancozeb (Dithane Rainshield F45): 1.6 qt/A; PHI 180d, REI 24h. Begin applications after spears have been harvested.
mancozeb + azoxystrobin (Dexter Max): 2 to 2.2 lb/A; PHI 180d, REI 24h, Groups M03 & 11. Begin applications after spears have been harvested. Rotate with a non-Group 11 fungicide.
FRAC Group M05:
chlorothalonil (Bravo Weather Stik): 2 to 4 pt/A; PHI 190d, REI 12h. Do not apply within 190 days of the harvest of spears in the following season.
FRAC Group P04:
laminarin (Vacciplant): 14 to 22 fl oz/A; PHI 0d, REI 4h.