IN YOUR ORCHARD
TIME TO CONSIDER
The dormant period is a good time to review changes in
management practices and determine if they have had
a positive impact on the profitability of the operation.
Consider the perceived or realized benefits of tree
health, the amount and expense of products applied
and irrigation practices. What should be improved next
year
?
What inputs should be increased or decreased
?
What practices had the greatest return on investment
?
This end-of-year review should also take into account the
following considerations.
Equipment Maintenance
Performing annual maintenance on equipment will help
maintain longevity and performance. Working on rigs
now will provide the opportunity to test equipment with
the dormant spray applications. Rig pumps should be
checked to determine if they are able to maintain proper
pressure. Nozzles should be checked to confirm that the
size and gallonage rate are to specifications. Plugged or
worn orifices, nozzles and swirl plates should be cleared
or replaced. Worn nozzles will reduce spray coverage
and increase pesticide usage, leading to lost money from
disease and insect infestation and off targeted pesticides.
Both spray and herbicide rigs should be checked.
Spur Sampling
Spur sampling should occur during the winter to
determine if delayed dormant treatments for scab or
scale are needed. With increasing scale pressures
observed, this practice is recommended for all mature
orchards. More information can be found by online by
searching “UC IPM Almond Spur Sampling.”
Winter Sanitation for Navel Orangeworm
(NOW) Control
The most effective way to reduce overwintering NOW
populations is sanitation. By removing the ‘mummy’ nuts from
the tree and destroying them by the end of February (when
moths begin to emerge), NOW damage at harvest can be
reduced. These nuts serve as the overwintering point for the
pupae and developing larvae, and are the ONLY in-season
food source for adults and second flight larvae.
The recommended industry practice is to reduce the
average mummy nut count to less than two per tree. This
recommendation was developed by performing research
and reviewing the data collected from plots throughout
the San Joaquin and Sacramento Valley. The research
showed that for every mummy nut left in the tree, one
percent damage from NOW should be expected. In other
words, five mummies per tree equals five percent NOW
damage. Therefore, in order to meet the industry standard
of two percent NOW damage levels, there should be
two or less mummies per tree. Recent research has shown
that a greater reduction of mummy nuts is needed in
areas with higher NOW pressure. In Kern County, they
have found that the standard for sanitation has to be less
than 0.7 mummy nuts per tree in order to keep NOW
damage below the industry standard of two percent. They
also found that the quantity of mummies on the ground
influences NOW damage: having more than 8.9 ground
mummies per tree increased NOW damage above the
two percent industry standard. These results were drawn
from research conducted over a 5-year period reviewing
data from plots established on fifty orchards.
By reviewing this data, does that mean everyone across
the state needs to sanitize to less than 0.7 mummy nuts
per tree
?
The short answer is “it depends.” Insect pressure
will vary by location due to more degree days and lower
rainfall that is generally characteristic of the southern San
Joaquin Valley and some micro-climates in the Sacramento
Valley. Regardless of location, all of the research indicates
that the fewer mummies within the orchard (both tree and
Mummies should be removed to reduce the overwintering
population of navel orangeworm. Mummies are the only food
source for larvae until hull-split next year. Pupae and larvae can
survive on kernels and hulls.
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A L M O N D F A C T S
