Fire Blight Infections Predicted With Rains on 2 April 2024 in Southern and Central Virginia

1. If today’s weather forecast predictions for 2 April become reality NEWA’s fire blight model is predicting that fire blight infections are possible this coming week with rains 2 April in Bristol, Cana, Rustburg, Tyro, Fincastle, Roseland, Roanoke and other Central and Southern Virginia locations on any pome fruit with open flowers: pears are in bloom from 14 March in Roseland VA and Pink Lady apples started opening first flowers today on this same location (Figures below, Source: No fire blight infections are predicted in Timberville, Winchester and Cross Junction. If wetting occurs on 2 April, fire blight infections are possible in central and Southern VA as the Infection Potential EIP value will rise to 104 in Bristol, 109 in Tyro, 154 in Rustburg (See figures below, Source: Use your closest station in NEWA at to determine the best course of action keeping in mind that EIP value must be 100 or above and the field with EIP number needs to turn dark red from orange to indicate “Infection.” Spray options against fire blight are:

SPRAY OPTION 1: preventive streptomycin – cover before the predicted wetting event any apple and pear trees in bloom with streptomycin: Harbor, or Agrimycin 17 WP, or Fire Wall 17 WP at 1.5 to 3 lb per acre (24 – 48 oz/A) plus LI 700 at a penetrating rate or use Regulaid instead of LI700. Based on the Regulaid label, you could use 2 pints penetrating rate. FireWall changed its formulation to FireWall 50WP and the rate to use this higher concentrated material is 8 – 16 oz/A. If rain does not occur, you can trigger the infection at EIP 100 or above if you provide water with a fungicide spray application, so if you are applying a previously planned fungicide application – add streptomycin to it. Option one is a must in large acreage apple and pear farms.

SPRAY OPTION 2: Only if you must, i.e. you want to see if model was correct, use OPTION 2: if you have a smaller acreage farm with apples or pears in bloom, you could wait and see will you get the wetting event or not on 2 April, because the showers might be spotty and occur on one location and not on the other. So, if you get the rain events on the 2 April, infection will occur and you will need to cover with streptomycin up to 24 h after the first rain event has started. Apply streptomycin in mix with Regulaid or LI700 up to 24 h after the infection rain event started (kick-back mode of application). In case you will use LI700 instead of Regulaid, use a penetrating action rate for LI700. If rain does not occur, infection will not occur, unless you provide water with a fungicide spray application near the infection dates, which can and will trigger the infection – so if you plan fungicide application add streptomycin to it.

You can add your fungicides to streptomycin to make the spray more economical, and keep the SI (DMI) fungicides + mancozeb (3 lb/A) about every 14 days for rust and scab. In between you can use mancozeb + either Fontelis, Sercadis, Miravis or Excalia (SDHI fungicides) for scab and powdery mildew.

WARNING: If you used captan recently, which would not be my choice, DO NOT add Regulaid or LI700 (at penetrating rate) to streptomycin for this bloom spray against fire blight.