With harvest season in full swing, I thought I would share with you an observation I’ve made over the years. I’ve noticed that gulls seem to congregate around fields being harvested. I am not sure what the attraction is, but my guess is that they are begging for food from harvest crews. Gulls are problematic in that they are known to be carriers of several human pathogens including E. coli O157, Salmonella and Campylobacter (Jay-Russell,2013). When gulls fly over fields, it is inevitable that some of their fecal matter will be deposited on unharvested crops, in irrigation canals and on harvest equipment (Figs 1-4). Obviously, when this happens, it is a food safety risk. Despite the significant effort and investment made in bird deterrent technologies, I am not aware of any that are effective and reasonably priced for gulls. The best advice I have for reducing the risk of food contamination from gulls is to be vigilant about instructing workers not to feed the birds and locate food trucks away from crops to be harvested.

References
Jay-Russell, M.T. (2013). What is the risk from wild animalsin food-borne pathogen contamination of plants?. CABI Reviews 4(8),1-16.https://doi: 10.1079/PAVSNNR20138040

Fig. 1. Bird fecal matter on romaine lettuce.


Fig. 2. Gull flying over romaine lettuce being harvested.


Fig. 3. Gulls flying over irrigation canal near lettuce field
being harvested.


Fig. 4. Bird fecal matter on lettuce harvesting equipment.

Included below is a list of organic insecticides that you can consider for your organic IPM programs. Although there are few alternative organic insecticide options, it is important to rotate when possible. Like conventional insecticides, continuous exposure to the same biopesticides may pose some risk of further reducing their efficacy and leading to the development of resistance. 

A good organic insecticide rotation practice is to alternate selective organic insecticides with broad-spectrum organic insecticides. The use of selective organic insecticides favors the increase of beneficial arthropod populations which may help to keep the pest population in check and delay repeated application of insecticides. When the population of lepidopteran pests is low, spraying Bt-based insecticides first and pyrethrin or Spinosad-based products thereafter is a good strategy. Proper insecticide rotation is important because it can help reduce insecticide application frequency, resulting in reduced crop production costs. 

 Tank-mixing can help improve the efficacy of some organic insecticides against some target pests. Tank-mixing a Bt insecticide with pyrethrin, such as Xentari + Pyganic or Dipel + Pyganic, can be an effective combination for controlling lepidopteran larvae. Additionally, combining Pyganic and a neem-based insecticide like Aza-Direct can be a favorable combination for small lepidopteran larvae. Tank-mixing Entrust (spinosad) and M-Pede can help suppress flea beetles and bagrada bugs.