The specifics of pest scouting programs may differ by greenhouse operation, but there are also some universal principles to follow.
Q: When it comes to greenhouse ornamentals, what are your protocols for scouting, monitoring, and identifying a pest? How successful has that been?
Luxon: One of the most important aspects of pest scouting is record keeping. Keeping good records lets you identify historical problems and come up with preventative strategies for future crops. An example would be that if your scouting records indicate that your roses are infested with aphids every year by the end of June, you could plan a spray for the following year in late May/early June in an attempt to head it off. In addition to planning for the future, good notes/records allow you to look into the past and determine if a given course of action had the desired effect. Going back to our aphid example, perhaps every year in late June you have an aphid outbreak on roses. Looking at your notes, you’d be able to see that when you treated with chemical “X” it took three weeks for the aphid numbers to come down; however, when you treated with chemical “Y” you brought the numbers down in one week.
We scout all our crops once a week. The higher the frequency you can afford to scout a crop, the greater the chances are that you’ll catch a problem while it is starting to develop and before it is causing significant injury/damage. It is much easier to spray a patch of plants for a problem then spraying an entire greenhouse for a large-scale outbreak. Scouting for us consists primarily of walking through crops and randomly (trying to achieve a representative sample) pulling plants and trays and shaking/brushing them off over a white background and seeing what falls out. We also have large sticky trap cards positioned in certain crops and areas. As we pass by these during the weekly scouting, we will look at what has been caught on these cards and record anything noteworthy. In addition to the large trap cards, in certain crops we will also have small trap cards that we carefully count and record what has been captured on them. These small cards are currently being counted every two weeks; they are laid out evenly across the greenhouse and are being counted in an alternating checkerboard pattern. We are counting every week, but each card sits out for two weeks prior to being counted.
Another key aspect of pest scouting is being familiar with your crop. As you work with a crop over time, you will start to internalize what is normal for that crop at a given point in its life cycle, and when it deviates from that norm, you will be able to quickly realize that. Pay attention to stuff that isn’t behaving normally and dig down into it to try and see if you can find the cause.
The next part is making sure you know what you are looking at while scouting. For us, we commonly see the “Big 5” bug pests (I imagine this will be the same in most greenhouses): Aphids, spider mites, whiteflies, fungus gnat, and shore fly. We will commonly run into pests that are not from this list. My background prior to working at this greenhouse had me closely working with insects, and as such I had quite a solid knowledge base coming into this job of insects and how to use various dichotomous keys for identifying them. If an individual isn’t comfortable identifying insects, they are going to want to find and familiarize themselves with their local agricultural Extension for aid in pest identification and treatment.
Plant disease is also something every greenhouse will have to deal with. Thankfully a vast majority of the plant diseases that will pop up with any frequency can be prevented by careful cultural management in the greenhouse. Don’t allow excessive amounts of old, dead, plant material to build up in your greenhouse. Carefully clean areas after crops move out and before the next crop begins. Many root diseases can be prevented by proper watering practices. Likewise, a lot of foliar issues are preventable with proper airflow and wind current management. A lot of the diseases present very similar symptoms (e.g., a brown blotch on a leaf). As such, it is far more common to send off samples of diseased plants to an agricultural extension lab for proper identification. If you can accurately ID it, you can accurately treat it.
Q: What tips and tricks would you offer for pest scouting?
Luxon: Keep good records and keep them in such a manner that you can easily look back at and make use of. All the purposes of these records are explained above. Another recommendation I would make is that you need to make time for scouting. A small operation won’t have the same manpower that I have at my organization, so this may difficult, but prevention of a problem is much cheaper than treatment of a large outbreak. Try to make a commitment to scout once a week and make a point of looking back at records (as you acquire them) and try to establish patterns in pest problems.
Q: What pests right now are of the most concern in the ornamental market?
Luxon: Aphids are some of the more annoying pests that we run into, and I would imagine many ornamental greenhouse operations have had issues with them. Thankfully, there are quite a few treatment options available that are quite effective. The problem with aphids is that they can multiply and spread quickly, and once the numbers get high enough on a crop, they will develop winged (alate) forms that will travel to new plants to start another colony. While it would be rare for aphids to kill a crop outright, they will likely cause significant aesthetic damage to the plant to the point it will prevent sale. I would also believe that spider mites are going to be a very common greenhouse pest that can cause headaches for growers. Spider mites, like aphids, are capable of reproducing very quickly, and a small problem can quickly grow into a ruined crop. Also, like aphids, once the numbers get high enough, spider mites have a tendency to start migrating to other crops in the area and not just adjacent plants.
Q: What tools have you found to be useful when scouting and monitoring crops? What has made the tool so useful at your operation?
Luxon: In terms of results, simply getting out there and making a point of going through your crop and shaking plants out to see what is in them. I have a feeling that the small sticky cards are going to be one of our most powerful tools as new machine vision techniques come to market. One of the limiting factors right now in our utilization of sticky card traps is the amount of time it takes us to read/count what is trapped on a card. I believe in the next few years, simple AI vision techniques will allow us to simply photograph a card, and with reasonable accuracy a machine vision program will be able to quickly count and categorize what is on each card. Once we are able to reliably tie in pest numbers to actual objective measurements, I am equally sure that data mining of historical greenhouse records/data will start to yield surprising insights between numerous environmental and cultural factors/practices and pest control.