WARNING for All Virginia Locations: Fire Blight Infection Predicted for Wetting Event 14 April on any Apple and Pear Trees in Bloom
As the NWS weather forecast for 14 -15 April has changed as of this morning, and I warned you in the last 3 days that fire blight risk is high, now the NEWA EIP issued “INFECTION” warning in red box on 14 April (see print screens below) and we will have TWO fire blight infections occurring with the two predicted rain events on 14 April. This prediction was not visible yesterday and two days ago. Therefore, as per my previous blog, I would recommend OPTION 1: preventive use of streptomycin in this case – cover before the predicted wetting event any apple and pear trees in bloom with streptomycin: Harbor, or Agrimycin 17, or Fire Wall 17 WP at 1.5 to 1 lb per acre (16 – 24 oz/A) plus LI 700 at a penetrating rate or Regulaid. Based on the Regulaid label, rate which ranges from 1 to 4 pints per 100 gallons of spray mixture, I would use 2 pints penetrating rate. Keep in mind that FireWall has changed its formulation to FireWall 50WP and the rate to use this higher concentrated material is 8 – 16 oz./Acre. If you still have FireWall 17 WP in your shed use the rate of 24 – 48 oz./Acre as it is less concentrated. Below are the print screens from the EIP model. Option one is a must in large acreage apple and pear farms. If rain doesn’t occur, infection will occur if you provide water with a fungicide spray application during 13-16 April. Water in any form can and will trigger the infection – so if you plan fungicide application add streptomycin to it.
OPTION 2: Only if you must, and you are willing to risk, use OPTION 2: if you have a smaller acreage farm, you could wait and see will you get the wetting event or not on 14 April, because the rain might be spotty on 14th and occur on one location and not on the other. So, if you get the rain events on the 14 April infection will occur and you will need to cover with streptomycin up to 24 h after the first rain event occurred. Use streptomycin in mix with Regulaid or LI700 up to 24 h after the infection rain event (kick-back mode of application). In case you will use LI700 instead of Regulaid, use a penetrating action rate for LI700. If rain doesn’t occur, infection will not occur, unless you provide water with a fungicide spray application during 13-16 April which can and will trigger the infection – so if you plan fungicide application add streptomycin to it.