Feb 5, 2020Prepare for Seed Corn Maggots in Spring Melons
If you drive throughout the Yuma area, you can clearly see recently planted spring melons field. I saw one field recently that had just been listed for melon planting with a lot of produce plant residue in and on top of the beds. This reminded me of the threat of seed corn maggots on early planted melons, particularly given the colder weather we’re having this week. Seed corn maggot is a pest that is best avoided. Seed corn maggots are always a concern for melon crops planted from Jan-Mar, and are most prevalent under cool, wet weather; ideal conditions for infestations. Seed corn maggots can cause significant stand reductions in melons and other large seeded crops (e.g., cotton, corn, safflower) due to the maggots feeding on germinating seed, roots and stems of young seedlings and transplants. If larvae populations are high in the soil, replanting parts or all of an infested field is often necessary. Not only is this an inconvenience to the grower, but replanting is expensive and can disrupt harvest schedules. Unfortunately, once maggots have been found infesting the soil during stand establishment, there is usually nothing you can do. Thus, 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 seed corn maggot. Melon stands are more susceptible to seed corn maggot during wet, cool spring weather in which seed germination is slowed or delayed. These conditions (low soil temperatures, rainfall and/or excessive irrigation) give seed corn maggots a chance to develop in the soil and attack the seeds before they can emerge. However, I’ve also observed seed corn maggots take down direct seeded cantaloupe and transplanted watermelon stands established under warm, dry conditions when flies were abundant. Secondly, our cropping system plays a key role. Melon crops following produce are the most often attacked because seed corn maggot adults are attracted to freshly tilled soils with high levels of decomposing organic matter and will readily lay eggs in the soil (particularly moist soil). This includes heavy plant residue remaining after harvest of the previous lettuce or cole crop, as well as applications of composted manure prior to planting. Growers would be encouraged to delay planting melons into fields under these conditions. However, if growers decide to plant in these conditions, then it would be wise to use a preventative insecticide applied at planting to minimize the impact from seed corn maggot and give seedlings a fighting chance. A few alternatives are available that have shown activity against seed corn maggot and may be practical for their management in spring melons. For more information, visit Seed Corn Maggot in Spring Melons, 2020.
Name that Pest:To contact John Palumbo go to: jpalumbo@ag.Arizona.edu