What is in this article?:
- Many growers are still not using one of the best tools to monitor almonds’ most destructive pest — navel orangeworm (NOW).
Bentley said he is “frustrated because more people are not even utilizing NOW egg traps to monitor spring and summer moth activity.” Trece and Suterra make NOW egg traps.
These bait traps are filled with pressed almond meal and oil. “The oil is extremely important to attract the moths to lay eggs and should be 10 percent by weight. Do not put dry almonds in a trap and expect to trap eggs.”
• Black traps work best.
• Place one trap per every 10 acres, for at least four traps per orchard.
• Choose trees that are at least five trees in from the edge of the orchard.
• Hang traps at head height on the north side of non-pareil trees, 1 to 3 feet inside the drip line of the tree. • Avoid areas where traps will be hit with sprinkler irrigation.
For larger orchards, divide sampling blocks into portions that can be sprayed as a unit. Orchards that exceed 1,000 acres can be divided into larger sampling blocks, if conditions within each block are uniform.
• Change baits every 4 weeks or if bait gets wet.
• 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. Clean eggs after each monitoring visit.
• Graph numbers of eggs laid at each trap. This will give growers and PCA an idea of when new generations of navel orangeworm are laying eggs.
Bentley said PCAs and growers should look at the history of the traps over a three to five week period in season to determine NOW levels. Past NOW history in individual orchards is also a good element to consider determining the need for a pre-hullsplit spray.
It could be worth the effort. He said a well-timed May spray could preclude a hullsplit spray because populations were knocked down early.