IPM Scouting Report: Week of August 10-14


Apples are maturing. Codling moth trap numbers have remained high in some orchards and other insect pests noted on scouting reports include green apple aphids, European red mites, 2-spotted spider mites, and Japanese beetles. As some apple varieties near harvest, growers need to be vigilant about reading labels and watching pre-harvest intervals if they need to treat for codling moths or any other insect pest.  Disease-wise, most growers have done an excellent job of keeping up and maintaining fungicide spray programs and scouts are noting very little disease. There have been a few apples with some fly speck and some apples with white rot symptoms.

Really the only issue with peaches is that oriental fruit moth (OFM) trap captures have remained high for the past 2 months so growers have been on a regular spray advisory to prevent damage from OFM larvae.

In small fruit, spotted wing drosophila (SWD) trap capture numbers have been increasing in control traps placed near wild fruit that is not being treated with insecticides.  These traps have captured between 20 to 40 + in this past week. Where growers are spraying on a consistent basis, fruit is protected and generally trap numbers are 0 or possibly with 1 or 2 SWD captured.


Lack of rainfall is becoming an issue, especially in larger fields without irrigation or in any smaller plantings without irrigation.

Tomatoes are being harvested and given the disease pressure that many plantings had to contend with quality is good. Scouts continue to see septoria leaf spot, and early blight in both field and high tunnel production. The recent dry weather spell is slowing the spread of these diseases and later plantings look much better than early plantings. Many field grown tomatoes also have bacterial diseases and scouts continue to note yellow shoulder. Also in open field tomatoes scouts are seeing tomato sun scald on fruit from to much exposure to sun light. (See photo below) In high tunnel production leaf mold continues on some farms and late blight is showing up in a few high tunnels as well along with powdery mildew. Tomato hornworms appear to have run their course but scouts are finding tomatoes with stink bug stings in both field and high tunnel production tomatoes. Aphids are being seen in some high tunnels as well.

Cole crops planted for fall harvest continue to have pressure from imported cabbage worm, with some fields at or above treatment threshold levels. (See picture below) Japanese beetles and grasshoppers were also noted on some scouting reports as causing some light damage to cole crop plants.

Depending upon the planting date, vine crops range from bloom to harvest. There is a lot of cucumbers, summer squash, zucchini, and melons (cantaloupe and watermelon) currently being harvested. Powdery mildew is being found by scouts in virtually every planting and growers are being advised on maintaining a fungicide spray program to minimize damage from this disease. Downy mildew has been found in a number of cucumber plantings and some growers have been able to greatly slow or even arrest the development of the disease with a good fungicide spray program and some help from recent dry and hot weather conditions. Downy mildew has also been found in some plantings of cantaloupe.  Anthracnose and angular leaf spot are also commonly noted by scouts in many melon and fall squash and pumpkin plantings.  Plectosporium blight has been found in several pumpkin plantings as well.  Other diseases that have been noted, but that are not widespread, include phytophthora fruit rot, fusarium fruit rot and septoria leaf and fruit spot.  Insect-wise, cucumber beetles continue to be present at anywhere from light to threshold or above numbers, and squash bugs and grasshoppers have also been noted in scout reports.

Eggplant and pepper fruit are being harvested.  Sunscald is being noted on both crops by scouts on a frequent basis.  Anthracnose has been found on both leaves and fruit.(See photo below) Some fusarium wilt on eggplant was noted this week along with some bacterial soft rot in peppers.  In some eggplant plantings Colorado potato beetle numbers were very heavy, triggering a recommendation to treat.  Scouts also noted some flea beetles on eggplants.  In peppers, some growers are treating for European corn borer larvae to prevent damage.  Stink bug stings have been noted on fruit by scouts along with the presence of aphids and grasshoppers.

Green snap beans range from in bloom to harvest.  Scouts have not noted any disease problems in green beans, but a number of insect pests are present including bean leaf beetles, potato leaf hoppers, grasshoppers and Japanese beetles, although nothing at an economic treatment level.

Sweet corn ranges from plants at V-6 to harvest.  Corn earworm trap numbers remain very low, 0 in traps at 4 locations this past week.  European corn borer moth captures ranged from 0 to 8 at 4 locations.  Currently there is low disease and insect pressure in sweet corn.

Potato harvest is underway in many plantings or plants are drying down so insect and disease monitoring has ended on this crop.

Sun Scald

Sun Scald on Tomato, photo by Chris Smedley

Imported Cabbage Worm

Imported Cabbage Worm, photo by Chris Smedley

Anthracnose on pepper fruit

Anthracnose on pepper fruit, photo by Chris Smedley


Agronomic Field Crops:

Scouting has ended on a lot of field corn as corn enters the R3-R4 stage of development.  In some later plantings corn rootworm beetles and some Japanese beetles have been noted. (See photo below)

Soybeans range from R-2 to R-6.  This week, scouts started to find some aphids, although at very low numbers, but this will bear watching for later maturing fields. Stink bugs continue to also be at very low numbers, averaging less than 1 per 10 sweep sample. In some fields scouts are noting between 10-20% defoliation attributed to a combination of Japanese beetle and grasshopper feeding damage. Scouts are also finding some very small amounts of sudden death syndrome and white mold in some fields.

Alfalfa regrowth following  3rd cut harvest is slow, due to the current dry conditions. Fortunately potato leaf hopper numbers remain very low and are not causing additional stress  to alfalfa plants. Other insects being noted by scouts in alfalfa include grasshoppers, aphids and loopers.


Root Worm also known as Spotted Cucumber Beetle, photo by Kate Fike


Leave a Reply

Your email address will not be published. Required fields are marked *