A response to the question posed to us concerning how soon one should be applying water to Chateau (flumioxazin) sprayed in the furrows for weed control in strawberry.  The label says that this herbicide can be applied at a minimum of 30 days before transplant of strawberries, but it doesn’t seem to specify how soon to apply the water after application.

Probably the sooner you apply water to furrows the better, but in a study run by Oleg in Ventura County, Chateau was applied to furrows about a month before sprinklers were turned on and the herbicide was effective against several broadleaf weed species, including wind-dispersed weed seed that landed in furrows after application.

Chateau does not degrade and just remains on soil surface, provided furrows stay dry during that time. If the furrows get wetted enough to germinate weeds the herbicide will be sufficiently activated as well.

The residual efficacy of Chateau is diminished over time, but you can reapply it to furrows if needed – there is no co-distillation, so as long as there is no drift, strawberry plants should be safe. You can extend the control by reapplying it with shielded sprayer in-season as long as the strawberry plants do not have flowers and fruit (which is soon in Southern California but quite a bit later here in Watsonville and Salinas) and you do not intentionally overspray the beds (first photo below) .

Also, thinking about traffic going through the field after application, specifically the wheels of tractors moving through the furrows, it does create some breaks in the barrier that the initial application of Chateau has formed.   It might be interesting to do a little experiment with different levels of disturbance post-application to see how much efficacy really is affected.  However, remember that Chateau can be reapplied later on in December and January in the furrows in order to get better control since it will be catching multiple flushes and cohorts of weeds from both the seed bank and wind dispersal. 

UC IPM guidelines for Chateau in strawberry are available at:

www.ipm.ucdavis.edu/PMG/r734700411.html

The use of flumioxazin (Chateau) is extensively written about in this article.  Before this or any other product, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.

This is an announcement regarding a review of strawberry transplanting.  The meeting will take place at the ALBA ranch on 1700 Old Stage Road in Salinas.  We will review topics such as important qualities of strawberry transplanting, keys of plant chill and maintenance of second year strawberry plantings.

Link to agenda is here:

http://cesantacruz.ucanr.edu/files/170334.pdf

The program of this meeting will be presented in Spanish, with translation into English.

There is a stream of thought currently in the Watsonville- Salinas strawberry production district of gaining advantage with earlier plant establishment this year by dramatically reducing the amount of supplemental chill, which is the cold storage of transplants following harvest, for the day neutral varieties ‘San Andreas’ and ‘Monterey’.  This might stem from reports that a number of growers in Santa Maria did well in the 2010-2011 production season with a single day of supplemental chill, and furthermore it is standard for growers in Ventura County to plant ‘San Andreas’ with a single day of chill.  For some then, it does not then seem like too much of a reach that this might be a good strategy for the Watsonville- Salinas production district.

This is worth reviewing because it flies in the face of standard recommendations for these two varieties planted in this area. There are several things going on here that perhaps contributed to the ability of some growers in Santa Maria to produce well last year with a single day of chill.  First, on average last fall, transplants were harvested 10-14 days later than normal and this spring was cooler than usual, meaning a bit lengthier cold conditioning in the nursery field and less plant stress early in the season.  Second, ‘San Andreas’ does seem to be a variety which is affected less by supplemental chill than other varieties, that is to say that it might not need quite as much.

Still, the UC recommendations do not change.  UC Davis plant breeder Doug Shaw, who brought all of these varieties into the world and therefore has an abundance of knowledge regarding them, is not changing his recommendations.   He maintains that one would want to choose transplant harvest about October 18-20 and plant early November, with two weeks supplemental chill. In all cases, plants should be chilled a bare minimum of eight to ten days. 

Never forget that supplemental chill gives the plant vigor to forgive the tough conditions of transplanting.  Planting day neutral varieties in the Watsonville Salinas district with one day of chill to gain advantage of earlier plant establishment is very much like picking up pennies in front of a steamroller.   For a possible small incremental gain, one is risking total disaster.  One day of supplemental chill is NOT recommended for University of California day neutral varieties grown on the Central Coast.

One of the first posts to this blog regarded the importance of chill, both field and supplemental, to the day neutral (ie Albion, San Andreas, Portola, Monterey among others) strawberry varieties.  Right now, field chill in MacDoel is in the area of 600 hours, which is plenty, even in the light of the very warm stretch of weather that took place in September.  Still, be reminded that this abundance of field chill should not be considered to be a replacement for supplemental chill taking place in the cooler after the transplant has been harvested.

However, this year because of the delay in transplant harvest growers really should be striving to strike a balance between getting adequate supplemental chill to obtain good vigor and planting sufficiently early to get sufficient plant growth here in the fall.  To accommodate this idea, every one of the day neutral varieties listed above can be well established with supplemental chill of 7 to 10 days, but no less.  More days of chill, up to 18 days, are of course in the printed recommendations, but this year a large delay in planting may not result in acceptable plant growth and establishment.

If one follows the suggestion given above, supplemental chill will end up being on the low side, and subsequently growers must be more vigilant than usual in planting practices.  Transplants must not be allowed to dry out in the field during planting, transplants should be properly placed the planting hole (no “J” rooting, and only portion of the crown above the soil line) and irrigation for establishment should keep the beds at field capacity for a few weeks.