(D11) ORANGE: Citrus sinensis (L.) Osbeck, 'Hamlin' FOLIAR ...

Arthropod Management Tests 2013, Vol. 38

doi: 10.4182/amt.2013.D11

(D11) ORANGE: Citrus sinensis (L.) Osbeck, ‘Hamlin’ FOLIAR SPRAYS OF MICROBIAL INSECTICES TO CONTROL ASIAN CITRUS PSYLLID AND CITRUS LEAFMINER IN ORANGES: SUMMER, 2012 Philip A. Stansly University of Florida/ IFAS Southwest Florida Res. and Ed. Center 2685 State Road 29 North Immokalee, FL 34142-9515 Phone: (239) 658-3427 Fax: (239) 658-3469 Email: [email protected] Jawwad A. Qureshi Email: [email protected] Barry C. Kostyk Email: [email protected] Asian citrus psyllid (ACP): Diaphorina citri Kuwayama Citrus leafminer (CLM): Phyllocnistis citrella Stainton Asian citrus psyllid and CLM are important pests of citrus and responsible for the spread of huanglongbing and citrus greening diseases, respectively. Selective control measures are needed upon which to develop integrated management strategies against these pests to reduce the incidence of the associated diseases without undo impact on beneficial insects and mites. The experimental block at the Southwest Florida Research and Education Center consisted of 3-yr-old sweet orange ‘Hamlin’ trees planted at a density of 308 trees/acre. Trees were drip irrigated and subjected to conventional cultural practices as well as pruned and sprayed with 25-0-0 NPK at 1 gallon per 100 gpa to induce new growth for ACP and CLM infestation. Eight treatments and an untreated check, 9 trees per plot, were randomly distributed across 4 replicates in 8 rows using an RCBD. Treatments were applied on 7 May 2012 using a John Deer High Crop Sprayer operating at 180 psi with four ATR 80 yellow nozzles, two on each side to deliver 75 gpa. A second application of all treatments except Delegate WG was made on 21 May 2012. Evaluations were made at 2, 7, 16, 22 and 28 days after (the first) treatment (DAT). Eight randomly selected shoots per plot were collected and examined under a stereomicroscope in the laboratory to count dead and live ACP nymphs. Three fully expanded leaves on each shoot were examined to count CLM larvae. Density of ACP adults, ants, spiders, ladybeetles and lacewings was assessed using stem tap sampling method. Individuals were counted after falling on a white clipboard placed under a randomly chosen limb struck 3 times with a short length of PVC pipe. Data were subjected to ANOVA and means separated using LSD (P = 0.05) are presented. Significantly more dead nymphs were seen on the Delegate treated plots at 2 and 7 DAT relative to all other treatments and the untreated check (Table 1). Significant treatment effects were seen on live nymphs through 16 DAT but not 22 DAT. Fewer live nymphs were seen on Delegate + oil treated trees through 16 DAT relative to other treatments and the untreated check. Grandevo at 2 lb/ac without oil did not significantly reduce nymphs on any date, and oil alone only did so at 7 DAT compared to the untreated check. Grandevo at 4 lb/ac + oil significantly reduced nymphs at 2 DAT and 7 DAT. There was no significant effect on nymphs of either Grandevo or MBI 206 + oil compared to oil alone. Delegate and MBI 206 2 gal/ac with oil and oil by itself provided most reduction of ACP adults (Table 2). Grandevo at 3 or 4 lb/ac rate with oil was effective through 28 DAT and performed better compared to 2 lb/ac with oil. No significant effect was seen with Grandevo at 2 lb/ac without oil. Oil alone was as good as or better than any other treatment and also helped improve effectiveness of some products. Significant reduction in CLM larvae was observed through 22 DAT with all treatments. Greatest and most consistent effects were observed with Delegate followed by MBI 206 and Grandevo, all applied with oil or with oil by itself (Table 1). Grandevo at 3 or 4 lb/ac performed better than at 2 lb/ac. Ants were the most abundant predators and the only ones showing a significant treatment effect, with fewest seen on trees treated with oil alone although not significantly different from Delegate + oil (Table 3). 1


doi: 10.4182/amt.2013.D11

Table 1.

Treatments

Rate amt product/75 gpa or % v/v

Untreated check none 435 Oil 2% Delegate 25 WG + 435 Oil 6 oz + 2% MBI 206 + 435 Oil 2 gal + 2% MBI 206 + 435 Oil 3 gal + 2% Grandevo 2 lbs Grandevo + 435 Oil 2 lbs + 2% Grandevo + 435 Oil 3 lbs + 2% Grandevo + 435 Oil 4 lbs + 2%

Mean no. dead ACP nymphs/shoot

Mean no. live ACP nymphs/shoot

2 DAT

7 DAT

2 DAT

7 DAT

16 DAT

0.97d 7.31bcd 42.63a 8.16bcd 8.65bcd 2.50cd 9.59bcd 16.59b 13.58bc

0.08b 0.29b 14.29a 1.08b 3.21b 0.21b 1.17b 5.21b 1.04b

67.68ab 52.34abc 4.25d 45.68bc 26.19cd 74.56a 45.28bc 44.50bc 34.84c

68.92a 21.50bc 0.83c 14.13bc 18.08bc 87.71a 33.29b 21.50bc 26.46b

40.79a 28.04abcd 9.38e 18.17de 22.63cde 37.79abc 15.29de 22.17cde 39.33ab

Means in a column followed by the same letter are not significantly different (P > 0.05, LSD)

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22 DAT 53.83a 39.79a 45.88a 29.33a 65.33a 41.79a 47.42a 33.71a 38.79a

Mean no. CLM larvae/3 leaves/shoot 2 DAT 1.33a 0.28c 0.50bc 0.45bc 0.91ab 0.63bc 0.41bc 0.72bc 0.26c

7 DAT 16 DAT 22 DAT 1.00a 0.25cd 0.00d 0.00d 0.33bcd 0.80ab 0.29cd 0.46bcd 0.54abc

2.00abc 1.88abc 0.13d 2.00abc 1.46bc 2.08ab 2.63a 1.54bc 1.04cd

2.08a 1.00bc 0.25c 0.95bc 1.25b 1.08b 0.96bc 1.67bc 0.83bc


doi: 10.4182/amt.2013.D11

Table 2.

Treatments



Mean no. ACP adults/tap sample 2 DAT

7 DAT

16 DAT

22 DAT

28 DAT

1.17ab 0.42cd

4.33a 1.21cd

6.71a 1.50b

9.29a 2.00a

6.37a 0.71e

0.08d 0.08d 0.63bcd 1.45a 1.00abc 0.58bcd 0.67bcd

0.12d 0.63cd 2.21bc 3.21ab 1.88bc 1.88bc 2.00bc

1.38b 2.04b 7.17a 6.83a 3.25b 2.50b 3.42b

1.79c 2.29c 7.33ab 8.83a 7.21ab 3.75bc 4.83bc

1.50de 2.29cde 4.79ab 5.37ab 4.50abc 2.37cde 3.62bcd

Means in a column followed by the same letter are not significantly different (P > 0.05, LSD) Table 3. Treatments



Mean no. /tap sample Ants

Spiders

Ladybeetles

1.39a 0.47c

0.08a 0.01a

0.03a 0.02a

0.77bc 1.33a 1.21ab 1.39a 1.38a 0.89abc 1.30ab

0.04a 0.07a 0.07a 0.04a 0.12a 0.07a 0.08a

0.00a 0.03a 0.01a 0.04a 0.02a 0.01a 0.03a

Means in a column followed by the same letter are not significantly different (P > 0.05, LSD)

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