IPM Scouting Report: Week of August 3-7


Apples are ripening with some varieties at maturity. Codling moth trap numbers remained high in several orchards this week, so growers will need to continue with follow up insecticide applications.  White rot, another of our summer diseases was found by scouts on some apples in one orchard this week. (See photo below) Growers need to stay on a consistent fungicide spray program with intervals no longer than 14 days between applications to prevent both sooty blotch, fly speck and summer apple rot disease development. All apple maggot traps remained negative the week of August 3-7. Green apple aphid populations were at high levels, above treatment thresholds, in some orchards again this week.  Other insects noted at below threshold levels in orchards included European red mites and 2-spotted spider mites.

Some peach varieties are being harvested. Based on growing degree days since the second biofix date and continued high Oriental fruit moth (OFM) trap captures in several orchards, a biofix date for 3rd generation OFM was set. Both the peach tree borer and lesser peach tree borer moth showed up again in trap captures in a couple of orchards the week of August 3-7.  Growers have been advised to do some preventative treatment against borer damage.  Growers are encouraged to maintain fungicide sprays to prevent brown rot and scab.  Scouts did fine a few peach fruit with some symptoms of scab this week.  (See photo below)

Spotted wing drosophila (SWD) continue to be caught in traps.  In our IPM program we have traps in fruit that are being sprayed on a regular spray schedule to protect against SWD damage and we have traps in wild fruit populations that are not sprayed. Numbers in those wild traps are consistently higher than traps in sprayed fruit. Most often traps in sprayed fruit are at 0. Spray programs can be effective in controlling SWD damage. Commercial small fruit growers should be spraying ripe fruit and fruit that are beginning to ripen to protect against SWD infestation. Rotate between chemical classes of approved insecticides.

White rot

White rot on apples, photo by Chris Smedley


Peach scab, photo by Austin Pelyak


          No measurable precipitation this week. There were a few comments by scouts on their grower reports that plants needed water or were showing symptoms of moisture stress.

The most serious disease problems in both field and high tunnel grown tomatoes remain septoria leaf spot and early blight. Some early plantings have been finished off by the advances of these diseases.   This week late blight was found in some high tunnel cherry tomatoes.

Bacterial spot and canker can be found in field tomatoes and growers are being advised to not work with the plants when they are wet, practice good sanitation between infected and non-infected plants and maintain a copper spray program to suppress the disease. In high tunnel production scouts are finding fusarium crown rot, Fusarium wilt, leaf mold, botrytis gray mold, timber rot and powdery mildew.

Due to the fluctuations in soil moisture as we have gone from very wet soils to dry soils, blossom end rot is showing up on tomato fruit. This is not a disease but is related to a shortage of calcium in the fruit, most often triggered by moisture fluctuations. Other non-disease, environmental disorders that scouts are finding in both field and high tunnel production include yellow shoulder, catfacing and zippering.

Stink bug damage is being found on tomatoes and hornworms have been found in both high tunnel and field grown tomatoes. Scouts noted some moderate to high aphid numbers in a couple of tomato high tunnels again this week.

Many of the cole crop fall harvest plantings had imported cabbage worm numbers above treatment threshold this week and growers were advised to treat. Flea beetles were also above threshold levels on several of these plantings.

In vine crops, many plantings of summer squash and zucchini are being harvested regularly, fall squash and pumpkins are in bloom to some approaching harvest, cantaloupes are being harvested, watermelons range from fruit set to harvest, and cucumbers range from new plantings to harvest.  Downy mildew continues to advance and is being found by scouts on more cucumbers.  Scouts also found more possible downy mildew in cantaloupe and squash.  Samples have been delivered to the vegetable pathology lab at OARDC for confirmation.   Growers are being advised to use a fungicide spray program on a 5-7 day schedule to protect against downy mildew.

Powdery mildew is developing quickly on all vine crops and scouts were advising growers to get on and maintain a regular fungicide program to protect leaves and to protect developing fruit. Scouts noted plectosporium blight, as confirmed by the vegetable pathology lab at OARDC, on several plantings of pumpkins in several different fields across the county.

Bacterial wilt is being found both cucumbers as well as some fall squash and pumpkins.  Cucumber beetles, the vector of the disease were noted at above threshold levels in younger cucumber, squash, zucchini, and pumpkin plantings and growers were being advised to treat to prevent bacterial wilt.  Fusarium wilt is being found in some melons.

Angular leaf spot, a bacterial disease has been found across all vine crops and in many fields.  Anthracnose and alternaria leaf spot have also been found and growers need to be on a good fungicide spray program.  Phytophthora blight on squash fruit was found in one field. (See photo below)

Although not common, millipedes have been doing damage to some melons, primarily cantaloupe.  Scouts also noted the presence of squash bug eggs and nymphs.

Many pepper plantings are at the harvest stage.  In some plantings, bacterial spot is present and bacterial soft rot has been observed. Sunscald and blossom end rot were noted again on scout reports this week and some of the sun-scalded fruit have now developed secondary infections of botrytis gray mold. Grasshoppers, European corn borers, potato leaf hoppers and aphids were all found at low levels in some fields, along with damage from stinkbugs.   Eggplant overall is doing well but there are plants with verticillium wilt and anthracnose.  Colorado potato beetles and flea beetles were noted at above threshold levels in some field this week.  Japanese beetles are present in low numbers.

Green beans vary from newly emerging to harvest. Defoliation generally below threshold damage levels by grasshoppers, and Japanese beetles have been noted, although in some isolated areas of some plantings defoliation by Japanese beetles is heavy. This week scouts found Mexican bean leaf beetles in some green beans, some at economic threshold levels. (See photo below)

Sweet corn, due to staggered plantings, ranges from V-4 to harvest. Corn earworm moth trap captures ranged from 0 to 6 at 4 locations this week. This level still indicates a 5 day spray schedule for corn at green silk. European corn borer moth captures ranged from 0 to 6 between 4 trap locations the week of August 3-7. Feeding by, European corn borer larvae, Japanese beetles and fall armyworm larvae was noted by scouts this week.  The heaviest feeding damage is being done by deer and raccoons.  Scouts continued to find Northern corn leaf blight and corn rust this week.

Potatoes overall look good and some are being harvested.  Colorado potato beetle is at threshold levels in some plantings and under control in others. Low numbers of potato leaf hoppers and flea beetle were noted. Early blight and septoria leaf spot are showing up in some plantings. The occasional plant with blackleg is also being noted by scouts.

Phytophthora on cucurbits, by Chris Smedley

Phytophthora on cucurbits, by Chris Smedley

Mexican BLB

Mexican bean leaf beetle, Photo by Art Sigler

Agronomic Field Crops:

A lot of corn is in the R-1 to R-3 stage of development. Brown silks signal an end to scouting.  There was 1western bean cutworm moth captured between 2 trap locations this past week.  Deer and bird damage is also being noted.

Scouts noted soybeans at the R2 to R5 stage of development this week. Scouts are noting brown spot on the lower leaves of most soybean fields as well as Downy Mildew. (See photo below) White mold has been found, but typically just a few plants affected in scattered pockets.  Sudden death syndrome (SDS) was noted on some scout reports this week, but at very low levels, just a few scattered plants in a field. (See photo below)  Leaf defoliators including bean leaf beetle, Japanese beetles, grasshoppers and slugs have all been noted on scouting reports. In some fields the combination of defoliators has caused between 10-20% plant defoliation. Scouts are sweeping fields for stink bugs as they reach the R3 stage of development. Stink bugs were found at very low levels once again the week of August 3-7.

Alfalfa is being monitored for potato leaf hoppers. Populations are still low at this time. Many alfalfa fields have been cut for 3rd harvest and are regrowing.

Downy mildew soybeans

Downy mildew on soybeans, photo by Chris Smedley


Sudden death syndrome

Sudden death syndrome, photo by Austin Pelyak

Sudden death syndrome roots

Sudden death syndrome on the roots of soybeans, by Austin Pelyak


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