David Doll12 CommentsJanuary 16, 2021Diseases

Almond Fungicides and Bloom: Plan Your Work, Work Your Plan

Planning your fungicide program has multiple benefits, and now is a good time to start doing so. Time can be taken to identify fungicides and respective modes of action to develop a proper rotation strategy. It allows the ability to price and compare differing options that may swap materials at specific points. Finally, it gives the opportunity to review the labels of the materials to determine application requirements, and the need to include (or most likely exclude) additional materials. To determine the year’s spray program, several things need to be considered. These include anticipated weather during flowering, disease history, materials available, operational tolerance to disease, and the ability to spray (budget constraints). Dry weather during flowering will reduce the need to spray, while free moisture from rainfall or humidity/fog can increase disease pressure. If dry conditions are present, fungicide sprays can be withheld until conditions change. In these types of years, bloom typically progresses rapidly, making it difficult to spray due to the shorter duration. As the flowering period ends and petal fall begins, it may make sense to consider a “clean-up” spray for any infections that might have occurred. Having a history of disease increases the presence of the given disease’s inoculum. This means that as soon as any rain event occurs, this disease will begin to spread at a higher rate. If dealing with a previous outbreak of a disease, especially diseases that form wood cankers (e.g. Anthracnose, Monolinia, Phomopsis, etc), fungicide applications should occur prior to going into any wet period, and re-application should be considered for any rain events that occur 10-14 days after the previous application. This may mean multiple sprays during wet years to reduce disease inoculum. As incidence decreases in future years, the spray program can be gradually reduced. Available chemistries for disease

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David Doll5 CommentsMarch 6, 2019Diseases, Horticulture

Timing Fungicide Sprays: Thoughts for a Wet Spring

Improper timing of fungicides wastes money and leads to crop loss from disease. Over the years, I have seen several disease epidemics that were due to the improper timing of a fungicide spray. These were observed in both wet and dry years, indicating the difficulty and general misunderstanding of disease and spray application timing. Proper timing of fungicide applications is difficult. Operational constraints in applying fungicides leads to mis-timed (too early, too late) or poor applications (every other row, applying too fast). This is often a function of equipment availability, whether by grower/operation or custom applied spray. Add to this aspect the various layers of fungicide availability and delivery timing, the changing pathogens and disease conditions, as well as the general misconceptions of various diseases, it is very easy for problems to occur. In order to control diseases, as advocated in earlier postings, it is best to design a fungicide plan prior to the start of the season. This provides the opportunity to review reference materials and determine which fungicides are best for differing stages of the crop. This plan also creates the opportunity to provide options for differing modes of actions at each timing to help with pricing, and reduces the burden of having to put the plan together when the season has started (and there are several other demands). Personally, I like to design the plan for a wet year and remove fungicide timings if dry conditions occur. An example of a plan with different modes of actions can be found here. Diseases don’t just occur. They require a susceptible host, the presence of a pathogen and suitable environmental conditions. For most almond foliar or bloom diseases, the pathogen is throughout the environment and most of our varieties are susceptible to one disease or another. The largest variable

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David Doll2 CommentsFebruary 9, 2017Diseases

Almond Bloom 2017

Almond bloom is approaching fast. Based on local conditions and projected warm weather next week, bloom will probably be within 7-10 days. Conditions this year are wetter than they have been in the past which will be conducive to many almond diseases, including brown rot, shot-hole, anthracnose, and jacket rot. Furthermore, orchard access may be limited, reducing the ability to apply fungicides by ground rigs reducing coverage. Below are a few points to consider as we begin the 2017 season. Be prepared for several fungicide sprays. If wet conditions persist, a more conventional bloom spray program should be considered with an application around pink bud to 20% bloom,  an application at 80% bloom, and a petal fall spray. These regular sprays ensure coverage of the expanding floral tissues. Sprays should be made every 10 to 14 days in consistent rain, and every seven to ten days if  heavy rains are experienced.   Fungicide rotation is critical. With multiple fungicide applications, each successive spray should be a different fungicide mode of action. This is represented by the FRAC number. If using multi-mode of action fungicides, the fungicide used in the follow up spray needs to be different than both modes of actions utilized in the previous spray. Please review the modes of action for the various diseases and timings by using the Fungicide Efficacy tables outlined here. Almond relevant information is on page 31. Often wet winters are followed by wet springs. With the potential need of fungicides through the spring, it may be useful to mix in a broad spectrum fungicide at petal fall. This would provide the ability to apply the same mode of action twice in the same season. A spray program with this type of rotation could look like this: Pink bud: FRAC 9; Full Bloom: FRAC 3/11; Petal Fall:

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