What's New at the Farm? Dealing With Pests

The end of June and the end of planting is well within grasp. The bulk of the planting and transplanting is done; the last big direct seeded crop, fall carrots, were planted yesterday.  Cultivation is taking center stage now as we have a limited amount of time to kill the weeds before they become too big to handle mechanically. Weeds are funny this year as many seem to be way ahead of schedule. I saw Galinsoga the other day in full bloom; we usually don’t see that blooming until mid July anyways.

And speaking of pests, I saw Mexican bean Beetles skeletonizing the bean leaves this week; that’s way early for them. It pays to actively scout a couple of days a week to keep abreast of looming pest issues. Colorado Potato beetles are out in force. Spinosad is a good control for them. They can quickly devour potato crops in what seems like no time at all; the eggs hatch quicker as the temperatures heat up. Below 65˚F eggs should hatch in about two weeks, but once the temps warm up to say 80˚F, eggs can hatch in as little as four days.  So, if you see adults or eggs, the instars will be out and feeding before you know it.

There are a few controls for Colorado Potato beetles; the best are row covers and Spinosad (Entrust and/or Monterey Garden Insect Spray). I think the nicest potatoes we ever had here were grown under AG-15 lightweight row covers.

Of course there are a few drawbacks using row covers, namely weed control underneath them. We use lots of them here and every once in awhile something gets past us. Weeds running rampant under the covers is easy to miss as you can’t easily see what’s happening under the covers so once you pull the covers off you might see only weeds and not any crop. With proper management and frequent crop scouting, this happens infrequently throughout the season.


Mexican Bean Beetles can severely injure if not kill a bean crop. The adults look like a bleached out Lady Beetle; sort of a pale orange with spots; in fact they are members of the Lady beetle family. Here’s a couple of photos:

Adults

Larvae

Both stages are destructive.
 
Any contact pesticide like Pyganic will work on both stages of these critters. Bean beetles overwinter in bean vines and leaf matter so cleaning these up at the end of the season will help stave them off in the following year. 

Cabbage loopers are out and Dipel products will control them as well as other caterpillars. Loopers as opposed to cabbage worms look more like inch worms than regular caterpillars. As with all  insect pests there are sprays which will take care of the problem, or there are cultural controls which eliminate spraying and perhaps killing non target species and good insects. Cultural controls include row covers, crop rotations and hand picking; everyone’s favorite job.

We use row covers for crop protection and insect exclusion for many crops including cucurbits, brassicas and eggplant. Exclusion of insects offers the ultimate control and will result in the cleanest crops available. Once installed they cut down on the scouting intervals of the covered crops as no insects can get into the crop.

Crop rotations will help control populations by denying food for the insects. For example, say a field has squash on it for three or four years in a row, then the populations of squash bugs and cucumber beetles will get built up. Take those squash away for a year and that insect population will move or starve as they have nothing to eat. Rotation also breaks disease cycles as well as insect population increases. Some insects are bound to survive, and others will migrate into fields that have a crop to eat, but not all will survive. And with rotation, insects can’t build up a resistance to it like they can with pesticides.

And finally there’s hand picking – probably not everyone’s idea of a fun morning but not the worst job on the farm I can think of either. We use hand picking for control of adult Colorado Potato beetles when we trellis and prune our tomatoes. The beetles are often found this time of year mating, and can be dropped into a can of slightly soapy water or can simply be crushed. Crushing is usually done by one of two methods – placed between two rocks or between the thumb and index finger; your choice. One is faster but your fingers get all yellow.

Until next week, Brian