Test of antibiotics and adjuvants for fire blight blossom blight suppression on Idared apple, 2012

摘要

Two kasugamycin formulations, oxytetracycline (FireLine) and five streptomycin/adjuvant combinations were compared to streptomycin (Firewall) for blossom blight control. The test was established in four randomized blocks on 30-yr-old ‘Idared’ treesusing single-tree replications with border rows between treatment rows. All treatments were applied to both sides of the tree with a Swanson Model DA-400 airblast sprayer at 100 gallons per acre on 3 Apr (pink-early bloom), on 13 Apr (late bloom), and again on 20 Apr (most petals off). Four selected branches per tree, each with 25 to 40 blossom clusters, were inoculated by spraying to wet with a bacterial suspension containing 1X10 Erwinia amylovora cells/ml in the evenings of 3 Apr and 13 Apr, the daysof the first and second bactericide applications. Trees were not inoculated after the third application. Infection data were based on the number of blossom clusters present on the inoculated branch at the time of the first inoculation. A cluster was rated as infected if it had at least one blossom with fire blight symptoms on 7 May. Maintenance insecticides applied to the entire test block with the same equipment included: Asana + oil, Altacor, Assail, Lannate LV, Calypso, Delegate, Imidan, and Provado. Fruit finish was rated on harvested samples of 25-fruit per replicate tree on 28 Aug.