Continued from Page 38 due to misshapen or wrinkled kernels, perhaps due to increases in secondary pathogens. Stink bugs are generally less mobile than LFB, so feeding tends to be more localized (clustered) in the orchard. Additionally, monitoring or observing visual evidence of stink bug adults (Photo 4), nymphs, and barrelshaped egg masses, can help indicate whether they were the likely cause of fruit symptoms. Brown Marmorated Stink Bug BMSB has been present in California since 2008, but has only recently begun to move into some agricultural commodities (commercial kiwifruit detection beginning in 2014, peach in 2016, and almond in 2017). Because this is an invasive species with a very wide host range, minimal natural controls, and highly aggregative behavior, there is considerable concern as to the potential impacts should it become more widespread and established in California agricultural crops. To date in almond, reports of serious infestation and damage have been limited to a few orchards in Stanislaus and Merced counties, but it is important to be aware of how to determine the possible presence of this pest in almond orchards, and how to distinguish damage caused by BMSB versus other bug feeding. Evidence of feeding (hull gummosis from multiple feeding sites) and shell and kernel damage by BMSB seems to be similar to LFB (if occurring earlier in the season, before shell hardening) or other stink bugs (if occurring later in the season, after shell hardening), although the severity may appear greater for BMSB due to its aggregative nature (infest in larger numbers in clustered areas of orchards). Recent research by University of California Cooperative Extension (UCCE) Area IPM Advisor Jhalendra Rijal in the impacted orchards indicates that BMSB may move into almonds and begin feeding as early as mid- <strong>March</strong>, and may continue well into summer. Therefore, it may be difficult to distinguish whether hull gummosis, nut drop, and/or kernel damage observed in <strong>March</strong> and April was caused by LFB or BMSB feeding. If hull gummosis is occurring later in the summer, it may be difficult to distinguish between BSMB or other stink bugs. Researchers are actively working on traps and lures for LFB, but to date, none are commercially available. Fortunately, there are traps and lures available for BMSB. In addition to trapping and visual observations of the pests themselves (adults, nymphs, egg masses), taking into account landscape-scale characteristics and location of the damage in the orchard may help indicate the source of damage if occurring during the same time period as either LFB or other stink bugs. For BMSB, pay particular attention to border rows next to overwintering Continued on Page 42 Photo 4. Adult green stink bug on almond. Photo courtesy of Integral Ag, Inc. 40 Progressive Crop Consultant <strong>March</strong>/April <strong>2019</strong>
<strong>March</strong>/April <strong>2019</strong> www.progressivecrop.com 41