|
|
|
|
How to Manage PestsUC Pest Management Guidelines
SYMPTOMSRust appears as small, yellow spots on the upper surface of leaves. On the lower surface of the leaf these spots take on a rusty red appearance when the rust-colored spores produced in the lesions erupt through the surface. These spores are spread by air movement and infect other leaves to continue the disease cycle. Young twigs may be infected, but twig lesions are seldom seen on almond. COMMENTS ON THE DISEASERust occurs sporadically throughout almond-growing areas in California. It is most likely to become serious in orchards near rivers or streams or other locations where humidity is relatively high in spring and summer. The disease causes leaves to fall prematurely and will weaken trees if not controlled. The development of rust is favored by humid conditions, and the disease becomes worse when rain occurs in late spring and summer. Trees can be defoliated quickly when rust becomes severe. The rust fungus survives from one season to the next in infected leaves and possibly also in infected twigs. MANAGEMENTIn orchards with a history of rust, apply fungicide in late spring and summer to control leaf infections. Two or three applications may be needed in orchards that have had severe rust problems. To be effective, fungicide must be applied before rust symptoms are visible. To prevent the rust inoculum from increasing in late fall, apply zinc sulfate (20-40 lb/acre) in late October to early November to hasten leaf fall. Otherwise, the inoculum may build up, overwinter on the trees, and infect leaves the following spring.
More information on almond fungicides
PUBLICATION![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg){kind=logo}
UC IPM Pest Management Guidelines: Almonds |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
![[Precautions]](/IMAGES/btn-precautions_bul.gif)