Provides both contact and systemic control. Always read the label of the product being used.ĬOMMENTS: Streptomycin-resistant strains of fire blight bacteria are present in some areas. When choosing a pesticide, consider information relating to the pesticide's properties and application timing, honey bees, and environmental impact. The following are ranked with the pesticides having the greatest IPM value listed first-the most effective and least likely to cause resistance are at the top of the table. Not all registered pesticides are listed. Pesticide precautions Protect water Calculate VOCs Protect bees Varying degrees of bacterial resistance to streptomycin exist in California.
#Fire blight on apple skin#
If conditions conducive to fire blight development have occurred and frost conditions develop that are severe enough to cause the apple skin to rupture, retreat immediately. Rain or hail may require immediate respray of the orchard if temperatures conducive to fire blight development exist. Alternate day treatments are recommended in the Sacramento Valley whenever more than 500 degree-hours occur in conjunction with major bloom periods. Treatment for both areas are recommended every 3 to 4 days when accumulation exceeds 150 degree-hours (Sacramento Valley) or 250 degree-hours (North Coast). In the North Coast region, treat within 24 hours preceding rain when more than 150 degree-hours have accumulated. In the Sacramento Valley, treat within 24 hours preceding rain if 1 to 150 degree-hours have accumulated.
#Fire blight on apple full#
If possible, start the season with a full soil water profile so irrigation during bloom can be avoided. If the orchard is being irrigated, the humidity threshold is reduced to 80% relative humidity as measured outside the orchard. The accumulated degree-hour total is not reduced by continuous cool temperatures if the total has surpassed 400 degree-hours and has coincided with precipitation or simultaneous warm, humid infection periods of at least 57☏ and 90% relative humidity. In this case, the accumulation of degree-hours is then reduced to zero until temperatures again exceed 65☏. Accumulate degree-hours each hour of the day unless 3 consecutive days below 66☏ occur. For example, a temperature of 70☏ for 2 hours generates 10 degree-hours. One degree-hour equals 1 degree above 65☏ for 1 hour. Use of the degree-hour method requires a recording thermograph to obtain a continuous temperature reading in your orchard. One such model is the degree-hour model, which takes into account early bloom and periods of continuous cool weather, allowing adjustments in treatment timings. Newer degree-hour models are based on assessing actual conditions for bacterial growth and infection and also indicate when treatment is unnecessary.
This model recommends treating every 3 to 5 days until the end of rattail bloom regardless of changes in weather that would inhibit bacterial growth and infection. The UC model recommends the first spray when bloom and mean temperatures reach 62☏ in March, 60☏ in April, and 58☏ in May.
These models can be used to time antibiotic and copper treatments. Several mean temperature and degree-hour models are available to assist in predicting infection periods and the need for control. In California, average daily temperatures or degree-hours are used to schedule fire blight sprays. The timing of the first application is critical. Blossom applications of copper materials or the antibiotic streptomycin are necessary in some apple-growing areas to reduce the spread of fire blight bacteria.
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