What is in this article?:
- San Joaquin Valley pomegranate production has reached 30,000 acres, doubling from 2006 to 2009, and is expected to continue growing.
- Licensed growers, packers and marketers are expected to ship 30,000 boxes of Angel Red, a premium, soft-seeded pomegranate.
- Most of the 2010 Angel Red crop will go to Japan, a growing and discerning market for the California premium, bright red fruit.
There are numerous, potentially devastating pests, many associated with fruit appearance. This is a key marketing element for fresh market products.
However, the pesticides registered are few. Lannate is about the only one for most pests. There is a greater choice of organic products, but they can be overwhelmed by high pest numbers.
These include aphids and whiteflies. The cotton aphid, which can build up in the fall, deposits honeydew on the fruit resulting in rotten spots on the skin. Beneficial insects often are strong enough to control aphids.
A second scientifically unidentified aphid called the “pomegranate aphid” is pale green with short, pale cornicles, different from the cotton aphid with black cornicles. This aphid infests leaves of all ages. Unfortunately, it is not controlled by beneficials.
This aphid also deposits honeydew on the fruit resulting in sooty mold.
Admire was recently registered on whiteflies in pomegranates and may control aphids applied through a drip irrigation system.
Grape and Comstock mealybugs can damage fruit, particularly the latter. Again, mealybug honeydew deposits cause fruit rot. The Encyrtidae parasites can help control these mealybugs as they do in grapes. Biological control is effective, unless disrupted by Lannate or by Grey and Argentine ants protecting the mealybugs because they feed on the honeydew.
Honeydew from citricola and black scale can also cause sooty mold, which easily is washed off. However, the green spot left when the scale is removed is often off-color because it has been covered by the scale and did not get enough sunshine to color well. Too many green spots can downgrade the fruit.
Where orchards border cotton fields, greenhouse and ash whiteflies can migrate from the cotton to the pomegranates. Again, honeydew and sooty mold result from heavy whitefly numbers. Cotton defoliation may send even larger numbers of whiteflies into pomegranates.
Omnivorous leafroller (OLR) is a common pest in many San Joaquin Valley crops. On pomegranates, the caterpillars typically carve surface grooves where two fruit touch or where the caterpillar has tied a leaf to the fruit surface. The worm can tunnel into the fruit, allowing pathogens to develop and grow in the arils with no visual, external symptoms. Damage can reach 20 percent or more.
OLR can be monitored by pheromone traps to monitor peak flights. It is the second flight that is the most problematic and likely warrants control. Checkmate OLR and NoMate OLR products are approved for confusion technique control.
A second option is a B.t. spray like Dipel or Deliver applied at least twice, at 700 to 900 degree days (seven to 10 days later) after the second flight begins.
The third OLR generation causes the most damage in late summer. B.t. sprays can be used then, if warranted.
Navel orangeworm and carob moth can occasionally be found tunneling into pomegranates, usually entering from rotten spots.
Leaf-footed plant bugs can build into large populations in pomegranates. More than 100 nymphs have been found in a single pomegranate. They especially like split fruit and can be found year-round in pomegranates.
Unfortunately, leaf-footed plant bugs have many hosts besides pomegranates.
Removal of leftover fruit could reduce overwintering populations.
False chinch bug is a threat to young trees. Dense masses of these can kill infested shoots in less than day.
They can build in weeds, especially London rocket. When weeds dry up or are mowed, nymphs move over the ground and climb up the lower part of trees. Control weeds for the first year or two and if necessary, treat weeds and infested ground with Lannate.
Cherry leafhopper, thrips and alfalfa weevil have also been found damaging pomegranates.
Finally, flat mite is a major pest because it causes leathering or ‘alligator skin’ damage, rendering the fruit unmarketable. These mites are small and difficult to monitor. Many pomegranate farmers apply one to three sulfur dust applications starting in late June as a prophylactic to ward off flat mite.