The questions that come in stump many of us, but we often have ways of finding answers. Here's a recent request and Mary Lu Arpaia's response. She's one of our Postharvest Physiologist Specialists.
"I am an extension specialist in NH, and I work with (mostly temperate!) fruit/veg crops. A consumer has reached out to the NH Division of Public Health here, with concerns about an avocado they purchased. I'm reaching out to you because you have written some outreach materials relating to avocado, and I suspect that you are much more familiar with this crop than we in New Hampshire are.
Would you have any insights about red discoloration inside an avocado fruit (see attached photo)? It does not look like typical chilling injury to me. Any thoughts would be welcome. Thank you for your time!"
Mary Lu's Response:
"You occasionally see this problem in ripe fruit, especially in lower maturity fruit.
Anyway the best guess is that it is phenolics from the seed coat leaking into the flesh of the fruit.
Not dangerous but the affected flesh may be bitter. I would cut it out and eat around the discolored flesh which is surface only."
Consumers in far away places often will see problems that we in avocado growing regions may never see. Increasingly though, the fruit is grown not so close to home and has traveled long distances, been handled by many different people and treated in less than acceptable fashion. So we may see more fruit problems in California as we import more fruit.
2017 Pitahaya/Dragon Fruit Production Tour – Ventura
UC Hansen Agricultural Research and Extension Center
14292 W Telegraph Rd. | Santa Paula, CA 93060
Enter on Briggs Road Entrance
Phone: (805) 525-9293 |Fax: (805) 525-5475
Monday – October 2, 2017
Self Driven Tour-Volunteer Drivers Needed for Carpooling
Tour Itinerary & Agenda:
7:00 am Registration, Continental Breakfast, Welcome and Introductions - Ramiro Lobo, UCCE San Diego, Ben Faber and Jose Fernandez de Soto, Ben Faber UCCE San Diego
7:45 am Depart for MVP Ranch in Fillmore, CA. – Tour hosted by Jose Fernandez, UCCE Hansen REC and Ramiro Lobo, UCCE San Diego County
9:15 am Depart for Thille Ranch in Santa Paula, CA. – Tour hosted by Dave Pommer
11:00 am Depart for UC Hansen REC in Santa Paula, CA. – Tour hosted by Jose Fernandez de Soto, UC Hansen REC
12:30 pm LUNCH, Pitahaya Fruit and Ice Cream Tasting, Pitahaya Cutting Exchange
2:00 pm Adjourn
Topics to be Discussed/Highlighted:
- Overview of farming operations visited
- Variety selection, planting, trellis and growing systems (pots vs. soils, shade vs. full sun, etc.)
- Pitahaya or Dragon Fruit Irrigation and water quality Issues
- Pitahaya orchard establishment & economics considerations
- Pitahaya/Dragon Fruit Varieties, Pollen Collection and Pollination Demonstration
- Integrated Pest Management (IPM) for pitahayas and other specialty crops
- Pitahaya fertility management & fertilizer practices
- Nematode issues for pitahaya production
- Pitahaya/Dragon Fruit Tasting and cutting exchange – Please bring/donate fruit for the tasting and get feedback from other growers (10 pieces of fruit needed)
Register Online at: http://ucanr.edu/2017-pitahayaventura
Registration Questions: Contact Roland Hills - 858.822.7711 or Erin Spaniel - 858.822.7919
Program Information: Contact Ramiro Lobo - 858.243.4608 or Jose Fernandez - 760.996.4874
Last May/June during a hot period and soon after fruit set, avocado growers and PCAs in the Oxnard/Camarillo area were calling in about young fruit about he size of a quarter showing up with white spots. Cutting into the fruit there might only be a small black spot just below the injury. Because that's what it is, a wound response on the part of the fruit to a physical damage. This occurred on several orchards also in the San Luis Obispo area and it seemed to happen in orchards that had recently been sprayed for avocado thrips. No piercing-sucking insects were found at any of these sites. Insects that would feed by feeding on the fruit and causing damage and malformed fruit. Insects that could typically make probing inspections of fruit prior to laying eggs. No eggs or larvae were found in the fruit. Nothing like lygus bug, BMSB, Bagrada bug or other stink bugs was found.
Did it have anything to do with the spray? With the hot weather? With the hot weather and the spray? With the hot weather and the insects that came with it? Did it have anything to do with the hot weather? Did it have anything to do with insects?
And then late June, the calls stopped. No more damaged fruit was being found. And then a lone call from Cayucos. Damage was found on young and older fruit. New damage seemed to be occurring on the fruit that normally sets later in that northern area. The grower walked the orchard and didn't find any bugs. The PCA swept the grove for insects. A yellow sticky card was put out.
So far, no insect has been found on the fruit. So what caused and "is" causing the damage to the fruit? It's not clear. Fruit that was damaged in Oxnard back in late May was tagged to see if it recovered. Ten fruit were flagged and two months later, those tagged fruit were still on the trees. So either the fruit that was attacked fell off with the initial damage or the fruit observed later had healed itself. Fruit have this capacity when they are actively growing to cover over damage. Often it is malformed. In most of cases with this fruit, the damage was very superficial. Occasionally, there deeper pits, but we didn't see any burrowing or tunneling.
If anyone else saw similar damage and has more to offer about this happening, I would be glad to hear about it.
Photos: Damaged fruit that was flagged and observed 2 months later.
- Author: Caio Brunharo and Brad Hanson
Article written by UC Davis PhD student Caio Brunharo from his dissertation research. It was originally posted in the September 2017 "Weed Management Notes" newsletter from the UC Cooperative Extension office in Glenn County by new weed science and agronomy Farm Advisor Mariano Galla (also a UCD PhD student in weed science!).
Take care, Brad
Italian ryegrass management in perennial crops in California
Caio Brunharo1 and Brad Hanson2
1PhD Candidate, UC Davis; 2UCCE Weed Science Specialist, UC Davis.
Italian ryegrass (Lolium perenne L. spp. multiflorum (Lam.)Husnot) causes yield losses in a variety of cropping systems around the world (Figure 1). This species is highly competitive with annual crops but may also compete with perennial crops particularly during the establishment years when they are most vulnerable to direct competition. In orchards and vineyards, ryegrass infestation can also interfere with cultural practices during the bearing years.
Repeated herbicide use has selected Italian ryegrass populations resistant to a variety of herbicide mode of actions across the world. Glyphosate-resistant Italian ryegrass populations were first reported in California in 2008, and the evolution and spread of these populations in the state made alternative postemergence herbicides an important management strategy against this troublesome species.
Recently, poor control of Italian ryegrass with Gramoxone 2.0 SL was reported in a prune orchard near Hamilton City, California. Greenhouse dose-response experiments and field trials were carried out to evaluate Italian ryegrass response to several postemergence and preemergence herbicides.
Our greenhouse studies confirm that the Italian ryegrass population from Hamilton City is resistant to Gramoxone 2.0 SL, Envoy Plus, Roundup PowerMAX and Osprey, whereas Fusilade DX, Rely 280, Simplicity CA, Matrix and Poast controlled both a known-susceptible and resistant Italian ryegrass population (Table 1). (note: Osprey and Simplicity CA, which are not registered in perennial crops, were included in the study for comparison purposes). Our criteria were that whenever the resistance index (RI) was larger than two and the comparison between biotypes was statistically different (P <0.05), the population was considered as resistant to that particular herbicide. Matrix is an exception, however, because this herbicide controlled both biotypes at well below its recommended field rate.
The field experiment with postemergence herbicides corroborates with data from the greenhouse studies, since glyphosate and paraquat did not adequately control the herbicide-resistant population from Hamilton City. On the other hand, most of the treatments containing Rely 280 were effective for control of the resistant population (Figure 2).
From the preemergence herbicide trial, all treatments containing Alion controlled the resistant population up to 150 days after herbicide application. Chateau, Surflan AS, GoalTender, Prowl H2O, and the tankmixes of Chateau + Prowl H2O and Chateau + Surflan AS exhibited control percentages above 90% with long lasting residual activity (up to 150 days after treatment; Table 2).
Even though several postemergence herbicides controlled Italian ryegrass in our research, it should be noted that ryegrass populations resistant to Fusilade DX, Rely 280 and Poast have been reported elsewhere in the state (data not shown), and overreliance on these herbicides will increase the chances of selection of further cases of resistance. A chemical weed management program in areas infested with Italian ryegrass should include a preemergence herbicide with long residual sprayed in the winter (Alion, Chateau, Surflan, GoalTender or Prowl H2O are possible options) tankmixed with an effective postemergence herbicide. In areas where herbicide-resistant weeds are known to be present, alternative herbicide chemistries should be adopted (rather than increasing the herbicide rate sprayed) in both the winter and spring application. In some cases, a short residual grass herbicide included with the post-harvest burndown application may help reduce recruitment of early-germinating Italian ryegrass plants which will reduce weed pressure and densities to be managed later in the season.
- Author: Kris Tollerup
0University of California Cooperative Extension Area-wide IPM Advisor, Kearney Agricultural Research and Extension Center, Parlier, CA
Leaffooted Bug Populations in Ventura County - 2017
Cold winter temperatures can reduce populations of leaffooted bug, Leptoglossus zonatus (Dallas), by ~50 to 80%. But unfortunately, it takes a cold year much like occurred in January of 2007 when daytime temperatures remained low and nighttime temperatures reached about 20° F for several hours. In other words, ouch for the citrus crop. Fall and winter temperatures of 2016 / 2017 were ideal for leaffooted bug and the 2017 growing season started out with large populations. I need to add that we do not fully understand if the wet winter positively affected populations - it certainly did not have a negative impact. Moreover, it appears that leaffooted bug populations going into later 2017 will be very large.
Monitoring and managing leaffooted bug presents an IPM challenge. In the fall between September and mid-November, the species produces a full generation; certainly, on pomegranate and although I have not observed it, also on desert willow. In most years, adults move from those host plants by late December to protected overwintering sites such as Mediterranean fan palm and Italian cypress trees; and perhaps citrus. In early March leaffooted bug leave overwintering sites to feed on what happens to be available at the time. In the San Joaquin Valley and the Sacramento Valley region it is almonds and pistachio. In other parts of California, where those nut crops are not available, citrus may be an important host crop. In Louisiana, for instance L. zonatus can cause considerable economic damage on satsuma mandarins, however in California the species has not been reported as a serious pest on any of the citrus cultivars.
The IPM challenge is that we do not have an effective monitoring tool to detect the bug when they leave overwintering sites. And moreover, once leaffooted bug is detected, no economic threshold exists , and pyrethroids offer the best management option – not necessarily the best IPM option.
Given the importance of pomegranate in the life cycle of leaffooted bug, PCAs and growers need to concentrate monitoring efforts on that crop during September through October, especially focusing on unmanaged orchards and hedgerows. If populations are found they will consist mainly of immature stages and there are two management options, clothianidin and pyrethrins. The caveat is that those compounds have only contact activity; coverage must be good and the insecticides will likely not have a great impact on adults because they will spook and fly away before being sprayed. Two organic compounds, pyrethrin (PyGanic) and Beauveria bassiana Strain GHA (BotaniGard) can also be effective. But again, those compounds have no residual activity so the spray must contact the bugs to be effective.
Insecticide use should occur only if monitoring indicates the presence of leaffooted bug and/or its feeding damage. Apply insecticides only after considering the potential risks of the compound to beneficial organisms, including bees and biological control agents, and to air or water quality. For more information on these topics please consult the UC IPM Pest Management Guidelines for Almonds at http://ucipm.ucanr.edu > Agricultural pests > Almond
(Ben: This insect became prominent in Ventura in 2015. Kris was minding his own business when he saw this bug traveling at 50 mph down the road.
Fig. 1. Aggregation of leaffooted by on pomegranate in early October of 2016. The aggregation is comprised mostly of fifth instar.
Fig. 2. Adult leaffooted bug on pomegranate in Ventura County, September 8, 2017.