- Posted By: Mark Bolda
- Written by: Mark Bolda
A few more comments on the situation with European grapevine moth in blackberries:
1- European grapevine moth is a surprisingly small moth, as one can see from the picture below. The larvae are also very small, so if you find a leafroller longer than a quarter inch in your blackberries, it is assuredly light brown apple moth or another leafroller and not European grapevine moth.
2- More information on the slim possibility of blackberries as a true host of European grapevine moth. Colleague Lucia Varela has provided me with a paper from the European Journal of Entomology (Stavridis, 1998) finding that European grapevine moth larvae did not survive when reared on blackberry fruit or flowers, but then a doctoral thesis from the Université Bordeaux 2 in 2002 identifies Rubus as a potential host. One of the crucial pieces of evidence for this identification is a book written by a P. Marchal in 1912, which we have not been able to find in order to confirm the citation as legitimate (if any of the readership here knows of a copy please let me know! It's pretty important). Underlining the dubiousness of the blackberry-as-host hypothesis, researchers in Europe, where this pest is native, have never seen European grapevine moth on many of the hosts cited in the work above.
3- A number of fields have been inspected, and as expected all have been found to be negative for European grapevine moth. Additionally, as a testament to the success area blackberry growers have had in controlling light brown apple moth, I have not heard of any finds of that pest either in these inspections. The regulations have been modified a bit now so that growers being inspected for European grapevine moth every thirty days are considered as inspected for light brown apple moth at the same time.
The photo below is of the inspection process (which takes from 20 to 30 minutes), and, as described before in this space, it is fruit by fruit. The inspectors are professionals, very thorough (and friendly too) and there is no doubt they will find larvae if they are present.
- Posted By: Mark Bolda
- Written by: Mark Bolda
As previously noted in this space, European grapevine moth has been found in this area and there is some regulatory action directed towards it. Blackberries, while an unfavorable host for European grapevine moth, are still identified by regulatory agencies as a host and thus subject to regulatory activity.
The following description of what regulatory activity in blackberries is going to look like was kindly provided to me by Leah Gayagas from the USDA PPQ.
A 5 mile radius of regulatory rigor has been drawn around the initial two European grapevine moth finds on Pleasant Valley Road. For us in the berry business, blackberries are the only ones identified as possible hosts, so raspberries and strawberries are not included in this list and are not of concern.
Currently, what this regulatory activity means for blackberry growers in this 5 mile radius is that there will be inspections of their production fields.
In field inspections will consist of the grower assigning some of his or her pickers to retrieve at least 20 lbs of harvestable fruit from a pattern which covers the whole field, which would probably consist of a trip around the perimeter of the field and then a ‘Z’ pattern on the inside. Considering what is at stake here, it would be best for the grower to assign the best of his or her crew to this assignment to make sure the very best of the field is harvested.
Harvested fruit are then lain out on a table and closely inspected by USDA personnel.
What follows is quite important:
Any suspect leafrollers from this 20 lb minimum fruit sample are forwarded on to the identification lab in Sacramento, be they light brown apple moth, orange tortrix or European grapevine moth or whatever- it all goes. In the very, very unlikely event of the collected leafroller being European grapevine moth, the field will be closed. In the unfortunate event that the leafroller is light brown apple moth, the field will be subject to a hold and then have inspection and pesticide spray protocols applied as has been standard for this pest. So, growers in the area currently under the 5 mile European grapevine moth inspection radius should be aware that are also in effect being inspected in the field for light brown apple moth.
Please be on your toes people!
Blackberry growers in the Pajaro Valley should be aware that there are substantial numbers of light brown apple moth (LBAM) larvae active in many fields right now. The photos below outline what this pest looks like and what it is doing right now in our blackberry fields.
In the photographed field, there were on the order of 7-9 leafrolls per two feet of hedge in the heaviest infested areas and in excess of 80% of the leafrollers sampled in the photographed field were identified as having a very high likelihood of being LBAM. This is very concerning, since under the current quarantine enforced by the USDA, the presence of any leafroller in a field can be cause for significant delay of harvest much less outright field closure if an LBAM is found.
While clearly not the level of devastating 100% loss of harvest caused by field closure for a positive LBAM find, LBAM itself is also capable of causing some damage. As one can see from the photos below, damage ranges from incidental feeding on flowers resulting in blemished (thus unmarketable) fruit to heavier feeding causing abortion of entire laterals and the subsequent loss of fruiting potential there. In the field photographed below there was damage of some sort to one of every sixteen fruiting laterals.
Anecdotally, it appears that growers who kept up with changing out pheromone based twist ties every four to six months have very low populations of LBAM suspect leafrolls, while those who allowed pheromone coverage to expire before putting up a fresh set are tending to have heavier, in some cases very heavy, larval infestations. If one is not going to be using pheromone based twist ties through the entire year, it is at least a good idea to put out a few pheromone traps to find out when adult males are starting to fly and looking to mate so as to better target use of mating disruption techniques.
As it seems many of the larvae being discovered currently are in the fourth to late instar stage (½ to ¾ inches in length), applications of Bacillus thuriengiensis formulations will not prove to be very effective. Better materials are the spinosyns, one of which (Entrust) is registered for use in organic fields, and bifenthrin (hard on beneficials though). Addition of a good surfactant is always a good idea to break spray water surface tension to facilitate movement of material into even the tightliest wound leafroll.
There are several insecticides mentioned for control of light brown apple moth in this article. Before using any insecticides, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.
This article is to share some information regarding orange rust in blackberries on the Central Coast. Apparently, this fungus was detected last year and it continues to spread. Previously only seen in some local plantings of Chester blackberries it has now been found on several occasions in proprietary blackberry plantings. Orange rust is a tough disease to deal with, so it is worth being able to identify and knowing what steps one needs to take to mitigate its spread.
Orange rust is caused by two fungi, Arthuriomyces and Gymnoconia which are distinguished by the shape of their spores and life cycle length. Their growth is favored by cooler temperatures and high humidity. While it is not common that orange rust infected plants die outright, their ability to produce fruit is severely compromised.
As readers can clearly see in the photos below, orange rust is hard to miss in the field. From further away, infected canes have a spindly appearance and on approaching one will see the upper leaf margins of both primocane and floricane framed with the distinctive orange of the fungal infection on the underside of the leaves.
Of all the rust fungi that we deal with in caneberries on the Central Coast, orange rust is unique in that it grows systemically in the plant, meaning that the most important management tool for growers dealing with an infestation of orange is a shovel. There is no effective fungicide for orange rust. Infected plants should be removed entirely, meaning all canes, leaves and the roots. This is best done before the pathogen spores are ready to be spread by rain and wind in mid-April through May.