We found our first striped cucumber beetle on Friday, May 20 and several more on May 23 (Figure 1). Given the cool weather, this is a little earlier than we
Figure 1. Striped cucumber beetles on melon plants (Photo by John Obermeyer)
would have expected. As the temperatures warm up this week, it would not be surprising for cucumber beetles to become very numerous in our melon and squash fields. Striped cucumber beetles are more attracted to squash so growers with those crops should look there first to see if the beetles are active in their area. Growers who direct seeded crops treated with FarMore® insecticide can expect about 3 weeks of control of striped cucumber beetles from that treatment. Growers who grow transplants from seeds treated with FarMore® will receive no benefit from those treatments once plants are in the field because the 3 weeks of control have ended. Likewise, growers who treated at planting with Platinum® or Admire Pro® can expect to receive about 3 weeks of control. Combining FarMore® treated seed with a planting time insecticide application will not provide any additional time of control. Once live beetles are present, growers must decide if a foliar insecticide application is necessary. Research has clearly shown that spraying weekly instead of only spraying when the economic threshold is reached will result in significantly lower yields, so only treat when necessary. For cantaloupes and cucumbers, the threshold is 1 beetle per plant, because these crops are highly susceptible to bacterial wilt, which is vectored by the beetles. For watermelons, squashes, and pumpkins, the threshold is 5 beetles per plant, because those crops are less sensitive to bacterial wilt. The pyrethroid insecticides, Ambush®, Asana®, Baythroid®, Brigade®, Danitol®, Mustang Maxx®, Pounce®, and Warrior®, will provide excellent control of striped cucumber beetles.