Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Downy mildew, Phytophthora capsici and white mold have been found in Delaware lima bean fields in the last 7 days.
Preventative applications of fungicides for Downy mildew may be justified at this time in fields that have not yet shown signs of the disease. Use one of the following in fields that are flowering or in early pod set stage.
● Fixed Copper (Champ DP, 2.0 lb 58DF/A, Kocide 3000 1.25 lb DF/A or other labeled fixed copper product),
● Forum – 6.0 fl oz 4.18SC/A,
● Headline – 6.0 to 9.0 fl oz 2.1 EC/A,
● Phosphonate Fungicide (ProPhyt -3.0 to 4.0 pts/A, K-Phite -1.0 to3.0 qt/A, Rampart -1.0 to 3.0qt/A, or Phostrol -4.0 pt/A, or other labeled phosphonate fungicide)
● Ridomil Gold Copper-2.0 lb 65WP/A.
● Omega – 8.0 fl oz/A (use only if white mold is also present)
If downy mildew has been confirmed in a field then use Ridomil/Gold Copper, or the phosphonate fungicides (ProPhyt, K-Phite, Phostrol, Rampart and others).
In fields that are being sprayed for downy mildew prevention Ridomil Gold Copper 2.0 lb 65WP/A or Forum 6.0 fl oz 4.18SC/A may suppress Phytophthora capsici.
In fields with white mold history, a preventative approach similar to snap beans can be used with a fungicide applied at 10-20% bloom and a second spray 10 days after if the soil remains wet. Later applications, when disease is present have also provided benefits.
Use one of the following fungicides for white mold control in lima beans:
● Endura–8.0 to 11.0 oz 70W/A
● iprodione–1.5 to 2.0 pts 4F/A or other labeled formulation
● Omega–8.0 fl oz 500F/A (also has good activity against downy mildew)
● thiophanate-methyl–1.5 to 2.0 lb 70WP/A or other labeled formulation
● Switch–11.0 to 14.0 oz/A 62.5WG