38 | FLORIDA GROWER | MARCH 2017 | INSECT CONTROL Save Your Cruciferous Crops From Diamondback Moths By Bonnie C. Wells [email protected] T he diamondback moth (DBM) is the most destructive pest of cab- bage and other cruciferous vegeta- bles worldwide, and one of the planet’s worst agricultural pests, wreaking havoc for growers to the tune of $4 billion to $5 billion dollars annually. The DBM is a perennial problem in the southern U.S. The caterpillars are extremely efficient at developing resis- tance to all classes of insecticides and are highly dispersive and adaptive to new environments, making outbreaks of the pest unpredictable. Insecticide resis- tance and the lack of natural enemies are believed to be the reasons why DBM is increasingly hard to control. What Growers Can Do Implementing an integrated strategy is critical to manage the DBM in cru- ciferous vegetable production systems. Pest management programs must focus not only on DBM, but also the entire crucifer pest complex, which includes numerous other caterpillar species, aphids, harlequin bugs, stinkbugs, and leaf beetles. This is because the presence of other early season pests is generally the motivation for use of preventative sprays in cropping systems and can decrease the presence of natural enemies and favor insecticide resistance. A truly integrated strategy will incor- porate several complementary tactics over large areas that work to suppress multiple pests. When used together, the following tactics can act synergistically to enhance pest suppression, reduce insecticide resis- tance, and improve the sustainability of the overall pest management program in crucifer cropping systems. Crop Rotation Because DBM has a narrow host range, feeding exclusively on cruciferous plants, crop rotation away from a host plant can significantly reduce the number of pests and subsequent damage in crop- ping systems. However, crop demand and price may dictate if crucifer-free periods are economically feasible for commercial vegetable producers. Trap Cropping Trap cropping, or using highly pest- attractive plants on field borders, can be used to intercept and retain pests such as the DBM and other crucifer pests. Collards and Indian mustard are recommended trap crops for suppress- ing DBM. Because collards are highly attractive to DBM, they can be planted on the periphery of cabbage or broccoli fields for pest management. Insecticide Knowledge and Resistance Awareness Insecticides have been widely used on cruciferous crops for the control of numerous pests. Preventative applications have been historically used for the control of early season pests and has led to the use of protective applications for later season pests such as DBM. However, use patterns significantly vary between regions and change depending on resis- tance development and new products becoming available for use. Because the control of the DBM has relied heavily on insecticide applica- tions, the pest has developed resistance This field of collards at the UF/IFAS Cowpen Branch demonstration plot in Hastings is serving as testing grounds for researchers to look at the efficacy of several different insecticides for diamondback moth control. Scientists also are conducting the same experiments on cabbage. Photo by Bonnie C. Wells An integrated approach is key to managing this destructive pest. Diamondback Moth Management.indd 38 2/14/17 3:47 PM