IN YOUR ORCHARD
TIME TO CONSIDER
dependent on environmental conditions. Heavy moisture or rain along with warmer temperatures will lead to the development of the disease. Symptoms appear as blossom blight, fruit infections, spur and limb dieback. Anthracnose is not a disease you want gaining a foothold in your orchard. It can have a multiple-year effect because of the infection to spurs and limbs. Growers may have to prune out the infection, in combination with a strong fungicide program to eradicate it. The diseases that cause growers so many headaches at bloom have been identified, but how do we control them ? There are quite a few fungicides that growers can choose from. The main thing to keep in mind is to pick the correct fungicide for the disease you are trying to prevent and the correct timing of when to apply the fungicide. In Figure 1, you will see a chart of different diseases and application timing. The chart is on a 0-3 scale with 0 being ineffective and 3 being most effective. This can help you target past disease issues. For example, if a grower has had a history of high jacket rot infection, that grower can look at this chart and know he/she needs protection at the full bloom timing. Now that we know when to target a specific disease, how do we know which product to use ? The UC Agriculture and Natural Resources IPM website has a great chart for this. Fungicide Efficacy—Conventional Products / Almond / Agriculture: Pest Management Guidelines / UC Statewide IPM Program (UC IPM) (https://bit.ly/3PNEf5U) The Almond Fungicide Efficacy Chart lists multiple products and the FRAC group associated with that fungicide. What is a FRAC group ? FRAC stands for “Fungicide Resistance Action Committee” and it is a set of numbers and letters to distinguish fungicides based on their mode of action. To prevent resistance to these fungicides, growers need to rotate FRAC groups to prevent developing resistant disease. That means if a grower’s first bloom spray contains a FRAC Group 3 fungicide, the second bloom spray application should not. The second should contain a different mode of action like a FRAC Group 7/11. By rotating FRAC groups it keeps tools in your toolbox. Growers have enough tools
Happy New Year! 2025 is here and while it may be a new year, growers will still be dealing with the same problems as bloom approaches: how to handle almond diseases throughout bloom. Disease in almonds can sneak up on growers, and once it starts it is almost impossible to stop. I will be discussing a few common diseases that present themselves during bloom and what you can do to prevent them. I am also going to talk about bees and how you can set yourself up for successful pollination. Being prepared for a weather event is critical to the success of a fungicide application. The first spring disease that usually pops into people’s minds is brown rot . The disease does need moisture, but not much. Brown rot can be present with little to no rain because there is moisture present in the flower itself and even the morning dew can set us up for a problem. The next disease that I’ve seen become a little more prevalent in my area is jacket rot/green fruit rot . This disease, like many others, must have the right conditions to be present. Jacket rot usually appears later in bloom when the fungus affects the dropping petals, jackets, or other flower parts and because of the moisture, they stick to the young almonds. It is most prominent in dense clusters of almonds because the falling plant material gets trapped in the cluster and can lead to infection of the whole cluster. Shot hole is another common springtime disease but has become less of an issue over the years. It is usually easy to discover as it develops small, reddish spots on the leaves, and typically has a dark spot in the center. These lesions can show up on other parts of the plant, but most people discover it on the leaves. Jim Adaskaveg, a leading plant pathologist at UC Riverside says shot hole “hasn’t been much of an issue over the past decade or longer, however, in large part because fungicides used to control other diseases have kept it at bay.” The last bloom time disease I would like to shine light on is anthracnose . Like the other diseases, anthracnose is
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ALMOND FACTS
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