Mating Disruption Trials
-- 2000
-- 2001
-- 2002

Insecticide Trials
-- 2001 & 2002

During these three trials, we have found that Intrepid and Confirm growth regulators combined with mating disruption provide levels of control equal to or better than conventional OP insecticides.

Mating Disruption Field Trial - 2000

Results

Use of the insect growth regulator trebufenozide (Confirm) by itself did not provide the level of codling moth control accepted by most commercial apple producers. However, when trebufenocide was used as a supplemental control tactic with mating disruption, codling moth injury was virtually non-existent (0% entries and 0.5% stings).

Table 1: Mean Percentage Fruit Damage at Harvest, 2000*

* Means in each column followed by the same letter are not significantly different (P=0.05, Fisher’s Protected LSD)

Table 2: Mean Percentage Fruit Damage at Harvest, 2001*

* Means in each column followed by the same letter are not significantly different (P=0.05, Fisher’s Protected LSD)

Results

In 2002, the cooperating grower found a high and unacceptable level of moths in the treated blocks during June. To save the crop and to prevent a build-up of moths in that section of the orchard, he began scheduled sprays of Guthion. Unfortunately, the experiment had to be abandoned at this point.

At the Iowa State University Horticulture Station (Link) in 2001, three tree blocks of Chieftain apple trees were treated with several insecticides in four replications. The sprays began at petal fall included Guthion 50W (1.8 lb/A) alternated with Imidan (2.5 lb/A) every two weeks; Guthion for one month, then Intrepid (8 oz/A) every two weeks; Avaunt (6 oz/A) every two weeks, then Guthion alternated with Imidan every two weeks; Guthion for first month, then Spintor (5 oz/A) every two weeks; Sunspray horticultural oil (0.75% by volume) every two weeks; and a non-sprayed control. Sprays were applied to both sides of the tree rows with a hydraulic hand-gun tractor sprayer. At the end of the season, 25 apples per tree were rating for codling moth stings or exit holes.

Similar experiments planned for Illinois in 2001 were abandoned early in the season due to a very serious fire blight epidemic.

In 2002, the Iowa experiment was repeated at the same site, however a new set of insecticides were tested. These included Imidan (2.5 lb/A) every two weeks; Danitol (18 oz/A) every 2 weeks; Diazinon (4 lb/A) every 2 weeks; Intrepid (8 oz/A) every 2 weeks beginning 150 degree days following biofix; Avaunt (6 oz/A) every 2 weeks for two months beginning 150 degree days after biofix, then Imidan every two weeks; Esteem (15 oz/A) applied for one month beginning 100 degree days after biofix, then a midseason rating and Imidan every two weeks; Sunspray horticultural oil (0.75% by volume) every two weeks; and a non-sprayed control. Biofix occurred when there was a weekly average of three moths caught in three traps in the orchard. Degree days were calculated as ((Maximum Temperature + 50)/ 2) – 50.
Data from both experiments were analyzed in SAS using the GLM procedure, and mean comparisons were made using Fisher’s protected LSD at p<0.05.

In Illinois in 2002, labeled rates of Guthion, Danitol, Avaunt, and Avaunt plus Guthion (1/2 rate of Guthion) were evaluated in comparison with a nonsprayed check on ‘Jonathan’ apples at the University of Illinois “Grein” orchard near Urbana. Single-tree treatments were used, with 5 replications per treatment in a randomized complete block design. Sprays were applied using a backpack sprayer at 30 psi at an equivalent of 100 gallons per acre. Because trees were young and first-generation flight was too light to warrant sprays or provide adequate pressure for evaluations, first applications were made approximately 240 F degree days after pheromone traps indicated a biofix for second generation flight. Sprays were applied on 3 July, 9 July (following rains), and 9 August; an absence of moths in traps during early July led to delaying the third spray until early August. On 4 September, all apples from all trees were harvested and examined for codling moth stings and entries. Data were analyzed in SAS using the GLM procedure and mean separations were made using Fisher’s protected LSD at P<0.05.

Result

In Iowa, horticultural oil and the non-sprayed treatment failed to provide an acceptable level of control in 2001 and 2002 (Tables 1 and 2). Several of the reduced risk insecticides, including Spintor, Avaunt, and Intrepid, provided excellent control when alternated with Guthion and/or Intrepid. Good control was also achieved with two insecticides that were recently labeled for codling moth, Diazinon and Danitol. Because the conventional controls (Guthion and Imidan) may have resistance problems and may endanger human and environmental health, we will recommend that our growers use any of the reduced-risk insecticides in their place.
In Illinois, Danitol was the most effective of the insecticides tested (99 percent more control than the nontreated check); Guthion, Avaunt, and Guthion plus Avaunt reduced injury by 76 to 88 percent in comparison with the nontreated check (Table 3). On-farm observations of the performance of these insecticides generally paralleled the results of this trial, but where resistance to Guthion has been documented, Avaunt, Danitol, and Intrepid also failed to give adequate control.