Alkaline treatments have been shown to reduce hull rot

Recent research has found that alkalizing treatments applied at hull split are able to reduce the severity of hull rot caused by Rhizopus stolonifer. Over the past two years, work by Dr. Jim Adaskaveg and colleagues out of UC Riverside has repeatedly shown that several products reduce hull rot incidence. These products included dipotassium phosphate (applied as the product diKaP) applied at 48 ozs/acre, calcium hydroxide applied at 320 ozs/acre, and Cinetis applied at 24 fl. ozs/acre. A single application of each of these products made at 5% hullsplit was shown to be as effective as several fungicide combinations and reduced hull rot strikes by over 75% in comparison to the untreated control. Multiple applications, with one made at early suture split (traditional first navel orangeworm (NOW) timings), did not seem to reduce strikes further. The cause of the reduction in strikes is unknown. It doesnt appear to have a fungicidal effect on the fungus as often the fungus is present within the hulls. The current thought is that these products neutralize the fumaric acid that is produced by this fungus (this is the acid responsible for limb death).  It could also be due to an increase in tolerance to the toxin from the foliar product. Work is ongoing. With these products, timing is key. Apply around 5-10% hull-split. Since these products may be tank mixed with NOW products as well as other fungicides, confirm compatibility by running a jar test. If struggling in managing hull rot, consider trying these products on a selected blocks to see if they provide any reduction in observed damage. Just remember to leave an area untreated in order to determine treatment effectiveness.  Finally, keep in mind that the use of these type of products for hull-rot enters the “grey world” of registration.  Follow appropriate

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Rhizopus and Kernel Issues

Rhizopus stolonifer, also known as the bread mold fungi, is a ubiquitous fungi. Within almonds, we often think of it as the Hull Rot pathogen, which can kill limbs through the movement of a produced toxin. Over the past harvest period, however, there have been some interesting kernel symptoms observed that have been found to be caused by this fungus as identified through isolations. The increased occurrence of these infections is thought to be due to the increased humidity experienced during the July, which most likely favored fungal growth. The first set of symptoms observed was the white fungal growth on the surface of the kernel (figure 1). The initial infection begins as a light, white fuzz that grows, and if left long enough in suitable conditions, begins to develop black spores. When these lesions were submitted for isolation, they came back as Rhizopus stolonifer. This type of kernel infection rarely becomes a concern because as the kernel dries to a suitable percentage for storage (~6% moisture), the fungal growth usually dries out and is not visible. It does not create a food safety issue. The second set of symptoms observed was a black or dark lesion that occurs on ‘Sonora’ kernels. These lesion tends to follow the “veins” of the kernel skin. The severity of kernel discoloring can vary, with most of the discolored kernels not providing an issue at processing. If, however, the infected areas are large enough, the kernels could get kicked out by the color sorters at the processors. When these kernels were submitted for isolation, we found both Rhizopus stolonifer and Aspergillus niger. Both of these fungi are common opportunistic fungi, and outside of the staining, the infected kernels do not pose a food safety concern. Thankfully, opportunistic fungi infecting kernels does not always occur. This

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