Drive around almonds orchards across the Valley and you’ll see growers and their crews busy on spring chores.
Except for a few rainy days, everyone has been busy applying fungicidesto tackle fungus and other diseases brought about by the wet weather and adding fertilizers and nitrogen to the soil.
|Mummy nuts left on the ground over the winter.|
“Many growers left so many mummy nuts on the trees,” she says.
That could spell trouble with navel orangeworm (NOW) down the road. NOW is the main pest of almonds. The mummy nuts serve as a winter home for NOW larvae.
That’s why Jenna stresses the importance of growers launching an aggressive mummy nut removal program during the fall and early winter. Without such a program, growers may wind up treating for NOW at hullsplit.
However, orchard sanitation apparently hasn’t been high on the to-do list for a number of growers. That means Jenna will be watching closely for NOW – as well as other pests throughout the season. To prepare, she has spent the past couple weeks placing traps for NOW and peach twig borer (PTB). (PTB is another pest, which overwinters in cracked bark and trunks of trees.)
|This is a PTB trap in placed in an almond orchard.|
For growers setting out their own traps, here’s a checklist from UC IPM:
- After setting the traps in early spring, check twice weekly to determine the biofix—this is the first of two dates in which egg laying increases in 75 percent of the traps in a given location.Jenna will set her traps seven trees deep from the edge and spaces them apart based on wind direction.
- Record the biofix date.
- Use traps baited with almond meal and 10 percent (by weight) crude almond oil. Black traps work best, but their caps do not need to be black.
- Place one trap per every 10 acres, for at least four traps per orchard.
- Choose trees that are at least seven trees in from the edge of the orchard.
- Hang traps at head height on the north side of nonpareil trees, one to three feet inside the drip line of the tree. Avoid areas where traps will be hit with sprinkler irrigation.
|This is one of the NOW traps Jenna will be monitoring.|
- Change baits every four weeks.
- Look for flat eggs that are laid mostly on the ridges of the trap or on the raised lettering on the top and bottom of the trap. Eggs will be white when first laid but turn orange-red before hatching.
- Graph numbers of eggs laid at each trap reading on the monitoring form. This will give you an idea of when new generations of navel orangeworm are laying eggs.
- Use this information to verify degree-day calculations. If you wish to use this information for timing a hullsplit spray, continue monitoring for the entire season.