THE GREEN SPOT 



Practical Scouting Techniques 



Mike Cherim 



V^ Scouting is the searching for 

 pests, diseases, or other 

 things detrimental to the 

 success of your crop. It's useful in 

 detecting and isolating problems be- 

 fore they get out-of-hand and is 

 critical to the success of any pest 

 control program, regardless of your 

 preferred corrective methods. Most 

 of the tips that follow are common 

 greenhouse techniques that can vary 

 from situation to situation. Some 

 can be applied to outdoor crops, 

 interiorscapes, etc. 



SCHEDULE. 



Scouting should be performed at 

 least once weekly and should not be 

 combined with any other activity. 

 Pick a day — and a time — in which 

 you are free to scout without inter- 

 ruption. Do not deviate. A lack of 

 consistency will affect the accuracy 

 of your information. (Choose a time 

 in which the greenhouses will nor- 

 mally be warm, well-lit — and quiet.) 



MAKE YOURSELF A MAP/GUIDE. 

 On a piece of paper, draw a scale 

 outline of your range, leaving plenty 

 of room on the margins for time and 

 date, notes, corrective actions, etc. 

 Within the outline, draw dashed di- 

 vider lines to mark off 250-square 

 foot segments. Number the segments. 

 Then make copies of the drawing. 

 Use one of these each time you 

 scout to record the findings of the 

 week. 



FOLLLOW A ROUTE 

 which takes you from section to sec- 

 tion — and stay on track. Starting in 

 the first section, check your monitor- 

 ing devices (sticky traps, etc.), then 

 go on to the next, etc. Then go back 

 to square one and repeat the circuit, 

 this time performing other scouting 

 techniques. 



USE MONITORING DEVICES. 



In each 250-square foot section, 



place one sticky monitoring trap. 



preferably a 3x5 yellow card. (In- 

 sects — whitefly in particular — are at- 

 tracted to yellow.) Vertically align it 

 so that it is perpendicular to the air 

 flow and 2-3 inches above the plant 

 canopy. If pests are being trapped, 

 change traps weekly; even if your 

 houses are clean, change them at least 

 once a month to insure viscosity. 



Monitoring for fungus gnats with a 

 sticky trap is slightly different: lay 

 the traps (adding one additional 

 trap per section) on or near the 

 growing medium, sticky side up. Or 

 you may want to use potato disks — 

 quarter-inch-thick cross-sectional slices 

 of raw potato placed on the media — 

 to record larval presence. You read 

 these by turning them over and 

 counting the number or larva that 

 have come up to feed. Change disks 

 weekly. 



Please note that one drawback to 

 using sticky monitoring traps is that 

 they may catch the good along with 

 the bad. If more beneficials than 

 pests are caught, temporarily discon- 

 tinue the use of traps, or use them 

 only every second or fourth week. 



Other monitoring tools include 

 magnifiers, pocket counters, and 

 blue traps (for thrips). For outdoor 

 use, sweep nets, field vacuums, and 

 pheromone-type traps (scent is the 

 attraction) or sticky traps in other 

 colors may be useful. 



TRY THE PAPER METHOD. 

 On certain preselected and num- 

 bered flowering plants (add these to 

 your map), pests can be detected by 

 tapping a flower or two above a 

 clean white sheet of paper. This dis- 

 lodges most pests and certain in- 

 sects — particularly thrips — can be 

 easily seen and counted. 



INSPECT TOTALLY. 

 Thoroughly investigate four or more 

 preselected, marked, and numbered 

 indicator plants in each section 

 (again, these should be on your 

 map). The number of plants will vary 



with the diversity of material. Con- 

 fine your inspection to only pre- 

 selected plants. However tempting it 

 is to inspect all the plants in the 

 section, don't. It's both unnecessary 

 and a waste of time. 



Using a I0x-to-30x hand-lens, first 

 check the new growth; then move to- 

 ward the middle of the plant and 

 check leaves — both top surface and 

 underneath. Do the same with older 

 leaves toward the bottom. Then, 

 look over the soil surface and, if 

 possible, slide off the container and 

 inspect the roots. Finally, move back 

 up the plant, studying stems and 

 nodes. 



As you proceed, jot down any ab- 

 normalities — deformed leaves, de- 

 cay, insects (ants may indicate the 

 presence of certain pests), insect 

 damage: anything out of the ordi- 

 nary. Take some leaf and insect 

 samples, if necessary. 



IDENTIFY. 



Before taking any action, be sure of 

 what you're seeing. Are these good 

 bugs or bad? Of economic impor- 

 tance? Once you've determined you 

 have pests, what species are they? 

 (For example, if you have whiteflies, 

 are they Greenhouse, Sweet Potato, 

 a Silverleaf variety, etc. ..it's impor- 

 tant to know — especially if you plan 

 to control these pests biologically.) 



Invest in a couple of guide 

 books — you can identify many of the 

 problems yourself. However, when in 

 doubt, take your insect or leaf 

 samples to your local university, co- 

 operative extension office, or private 

 service to be analyzed. The fee is 

 usually minimal; sometimes the ser- 

 vice is free 



KEEP RECORDS. 



By keeping weekly records — includ- 

 ing of what action was taken — you 

 can determine when, and possibly 

 why, a problem occurred. Data might 

 include pest population swings, growth 

 rate, in-house movement, suspected 



)une&)uly 1995 



13 



