The latest Arizona Vegetable Integrated Pest Management Update from the University of Arizona (UA) Cooperative Extension in Yuma, Ariz.

Seed corn maggots in spring melon plantings

By John Palumbo, UA Research Scientist and Extension Specialist

Last spring, seed corn maggots (SCM) caused problems for growers in early plantings of melons and cotton. In some instances, significant stand reductions due to larvae feeding on germinating seed required a few fields to be replanted.

Not only is this an inconvenience to the grower but replanting is expensive and can disrupt harvest schedules. Unfortunately, once maggots are found infesting the soil during stand establishment there is usually nothing that can be done.

Avoidance of the problem is the most effective way of preventing stand reductions. First, weather plays a major role in determining the damage potential for SCM to be a problem. Melon stands are more susceptible to SCM during wet, cold spring weather in which seed germination is slowed or delayed. These conditions give SCM a chance to develop in the soil and attack the seeds before they can emerge.

Another important factor is the SCM is attracted to fields with high levels of decomposing organic matter. This includes heavy plant residue remaining after harvest of the previous lettuce or cole crop, and applications of manure prior to planting. Growers are encouraged not to plant melons into fields under these conditions.

However, if growers decide to plant in these conditions, then use a preventative insecticide applied at planting to minimize the impact from SCM and give seedling stands a fighting chance.

A few alternatives are available that have shown activity against SCM and may be practical for SCM management in spring melons. Please see the publication Seed Corn Maggot Control With In-Furrow Sprays and Seed Treatments On Cantaloupes and Insecticide Alternatives for Preventative Seed Corn Maggot Control in Spring Melons.

Contact Palumbo: (928) 928-782-3836 or jpalumbo@ag.arizona.edu.