NOW pheromone formulations, being field-tested here as a
lure within a trap, should be available soon as a monitoring
tool for navel orangeworm.
Research findings presented at last year’s Almond Conference provided growers with information and insights for refining their spring pest management programs. Outlined below is the result of some of the latest research shared at the conference on scab and Alternaria control, navel orangeworm pheromone as a monitoring tool, new products and timing for spring sprays and sprayer calibration.
Scab and Alternaria
Plant pathologist Jim Adaskaveg (UC Riverside) discussed new products and timing for spring treatments to control scab. Spring treatments for scab should be made around twig infection sporulation.
Adaskaveg reported that resistance to the QoI (FRAC Group 11) fungicides and the SDHI (FRAC Group 7) fungicides by the scab organism continues to develop, and resistance to other single-site mode-of-action fungicides, such as the DMIs (FRAC
Group 3), could also develop.
He recommended following a resistance-management program to control scab, especially in problem orchards.
For an optimum program, growers should have started with a delayed-dormant spray of copper (1.5-2 lbs. MCE) and oil (3–4%) or chlorothalonil (4 pts.) and oil (3–4%). In October 2012, Bravo Weather Stik received a Section 2(ee) registration for dormant
application between Dec. 1, 2012, and Jan. 10, 2013, or before budswell, using the 4-pint rate. For next year, full registration of this use is planned through IR-4, with a change in PHI to 60 days and rate to 6 pints per acre. A delayed-dormant spray reduces
sporulation and delays production of primary inoculum, which delays the annual disease progression until midsummer. It also synchronizes scab management with Alternaria treatment timings as described later in this article.
Two treatments should be made post-petal fall with chlorothalonil, mancozeb, captan or ziram, which are all multisite fungicides with a low potential for resistance development. Treatments should be made around twig infection sporulation, between two and five weeks after petal fall. Follow labeled rates, and do not use oil with chlorothalonil at this time.
Spring treatments for scab should be made around twig
infection sporulation (top photo) versus not sporulating
Another new chemistry for use in this time period to treat scab in almond is dodine (Syllit), which was federally registered in 2012. California registration is pending. Research has shown that this material should be used at the 32-ounce-per-acre rate for consistent, high performance.
To prevent further development of resistance, QoI and DMI fungicides should not be used repeatedly for in-season treatments for scab. Use QoI and DMI fungicides in rotations or in mixtures. Never apply a single-site mode-of-action fungicide once disease
For Alternaria leaf spot management, develop a program based on the history of the disease in your orchard over the last two seasons. If the disease is increasing each year, plan to start
a program when there are warmer temperatures and consistent wetness periods from dew, rain or irrigation in the canopy, typically from early May through June. Use the disease severity
value (DSV) model for exact indices for predicting infection periods.
After the first fungicide application, make one to two additional applications in approximately three-week intervals.
DMI fungicides (FRAC Group 3), polyoxin-D (FRAC Group 19) and the new SDHI fungicides (FRAC Group 7) such as Fontelis or the premixture Luna Sensation (FRAC Groups 7/11) show excellent performance when used in mixtures or rotations. For example,
Fontelis or polyoxin-D should always be mixed or rotated with a DMI fungicide to prevent the selection of resistance.
ABC-funded project leader Ring Cardé (Entomology, UC Riverside) reported that components of the navel orangeworm (NOW) sex pheromone have been formulated as a lure for field
use, and will be available soon as a monitoring tool when combined with a trap.
The research leading up to this milestone has spanned more than three decades. The major component of the NOW pheromone was identified in the late 1970s, but until now, identification of the critical minor components has been elusive. Fortunately, recent breakthroughs have identified critical minor components as well as their proper blend.
A four-component blend will be formulated in a dispenser that is effective for four to five weeks in the field. The blend also provides opportunities to improve navel orangeworm mating disruption.
This 30-plus-year effort — much of it funded by the Almond Board — involved the work and collaboration of numerous UC, USDA and private researchers. Cardé reported recent key collaboration has been with Brad Higbee (Paramount Farming Company), Jocelyn Millar (UC Riverside), Bas Kuenen (USDA-ARS) and Walter Leal (UC Davis).
Spring Peach Twig Borer and NOW Sprays
ABC-funded researcher Frank Zalom (Entomology, UC Davis) reported on newer effective insecticides and flexible timing options for spring sprays aimed at both peach twig borer (PTB) and NOW. Zalom said the newer registered diamide insecticides (Altacor, Belt and Tourisimo) are effective against both PTB and NOW. The diamide insecticides are thought to be less toxic to natural
enemies than the organophosphate and pyrethroid insecticides. In addition, two applications of Bacillus thuringiensis (B.t.) Kurstaki have proved to be effective for both PTB and NOW. The addition of these materials adds to a very nice spectrum of effective and
selective insecticide options, which are covered in UC IPM Online.
UC IPM Online also details timing for spring sprays for both PTB and NOW. Zalom’s research continues to show that sprays timed to either one of these insects will also provide a degree of control for the other.
Newer materials for spring sprays add to a spectrum of
effective and selective insecticides to protect almonds from
Because effective tools and timings are only as good as the spray technology, the Almond Conference held numerous sessions on sprayer calibration and newer spray technologies. Franz Niederholzer (UC farm advisor), Brad Higbee (Paramount Farming Company) and Ken Giles (UC Davis) led the workshop “Spray Coverage: The Missing Link in IPM.” Joel Siegel (USDA-ARS, Parlier) also reviewed spray coverage during the Pest Management Update Symposium.
The workshop presentation
provided an excellent review of sprayer calibration. (Another valuable resource is the UC IPM manual, “The Safe and Effective Use of Pesticides.”
The workshop focused on optimizing the performance of air-blast sprayers. Niederholzer noted there are two important reasons for this: One is optimizing pest control, and the other is reducing drift and pesticide runoff from orchards. Responsible environmental stewardship and more stringent regulations require proper sprayer calibration and operation.
Uniform spray delivery throughout the trees is a challenge as the season progresses and canopies fill. This is particularly true for navel orangeworm control, when leaf, shoot and nut growth can reduce spray coverage on nuts in the upper canopy compared to early in the season.
Keys to proper calibration and operation covered in this presentation include:
- Proper droplet size;
- Proper nozzle selection, orientation and adjustments to effectively target the canopy;
- Balanced air delivery to displace that in the canopy, which is closely linked to ground speed;
- Sufficient air and liquid volume to give good coverage, once carrier air is delivered to the target; and
- Monitoring your results.
The Almond Board is funding research investigating new sprayer technologies, and this work will be covered in subsequent newsletters. However, Giles aptly noted, “Before buying new technology, give your existing technology the same attention you would give a new piece of equipment. Often, that can be just as effective as investing in new technology. But remember, that new
technology will require more attention, especially as it is integrated into your operation.”