University of Arizona a dot Cooperative Extension

Arizona Melon Insect Losses 2002

Kai Umeda
Maricopa County Cooperative Extension
University of Arizona, Phoenix, AZ

Introduction

A survey of the 2002 melon growing seasons was conducted to ascertain the incidences of insect pests, diseases, and occurrences of weeds. The survey was conducted for spring and fall crops of cantaloupes, honeydews, and watermelon grown in the state. Six crop consultants in central Arizona and in Yuma County were sent surveys and four completed surveys were received during November 2002. The completed surveys represented 36.5% of the state's total cantaloupe acreage in 2002, 61.4% of the honeydew acreage, and only 15% of the watermelon acreage (Table 1). The data for statewide melon acreages were obtained from the Arizona Agricultural Statistics Service for February 2003 at: http://www.nass.usda.gov/az/crops/2003/crop0221.pdf . The spring crops of cantaloupe, honeydews, and watermelons were generally planted during January to March 2002 with harvest conducted during May through July. The fall cantaloupe and honeydews were planted during July to August and harvested during September to November of 2002. No fall watermelons were planted in 2002 in the survey. The data is presented primarily as averages or as a range in some cases for the number of pesticide applications for pests.

Results and Discussion

All melons were treated for insect pests in 2002 (Table 3). All melons were treated at planting time for insects and 100% of the fall cantaloupes and honeydews were treated with a foliar insecticide, primarily for whiteflies. Ground dwelling insects, whiteflies, and cabbage loopers were treated in all of the melons. Ground dwelling insects in one situation required up to five applications of insecticides. Spring cantaloupes were sprayed once in Yuma by one respondent and no application of insecticide in Maricopa County by another respondent. Three to four applications were required for whiteflies in the fall cantaloupes. Spider mites occurred in watermelons and required treatment on some acreages. Beet armyworm also occurred but did not warrant any treatment. Leafminers were found on fall cantaloupes and honeydews and required up to two treatments. Aphids were not observed in 2002.

Powdery mildew occurred in all melons and accounted for most of the fungicide applications (Table 4). Vine-decline disease affected on 4% of the spring cantaloupe crop and up to 77% of the watermelon crop. Vine-decline disease was not observed in any of the surveyed cantaloupes or honeydews. In fall cantaloupes, an unidentified soil-borne disease was observed as were other unspecified foliar diseases on honeydews and cantaloupes. Viruses were not observed in 2002.

Over 80% of the cantaloupe and honeydew crops were treated with a herbicide compared with fewer watermelon fields being treated (Table 5). Most of the melon acreages were treated at planting time with few acres treated with postemergence herbicides for grass weeds. Pigweeds and purslane were problems on 24% of the spring cantaloupe fields with perennial grass weeds and nutsedge infesting 14% of the fall cantaloupe. A higher percentage of watermelon fields were observed to be infested with more weeds.

Three respondents provided estimates of melon crop yield reductions (Table 2). One respondent reported observed losses in spring cantaloupes and watermelons, one reported only spring melons, and one reported only fall melons. Weather conditions were cited consistently for causing melon yield reductions. Market conditions were cited for the highest yield reductions in spring cantaloupes and watermelons. Weeds, insects, and diseases contributed to slight yield losses. Powdery mildew, vine-decline disease, nutsedge, cabbage loopers, and spider mites were reasons for crop losses.

Table 1. 2002 Survey of melon acreage in Arizona


N=4
Spring cantaloupe Fall cantaloupe Spring honeydew Fall honeydew Seedless watermelon Seeded watermelon
Acreage surveyed 3303 2100 805 730 739 193
% of state total 36.5% (14,800A) 61.4% (2,500A) 15% (6,200A)
Average yield
(range)
749 carton/A
(660-900)
640 carton/A
(630-650)
967 carton/A
(700-1100)
855 carton/A
(710-1000)
36T/A
(23-50)
39T/A
(22-55)
Potential yield 750-900 630-750 1100 1100 45T 30T


Table 2. Observed melon percentage yield reductions


N=2
Spring cantaloupe Fall cantaloupe Fall honeydew Seedless watermelon Seeded watermelon
All factors 24 15 10 7 27
Weather 10 12 8 6 10
Weeds 0 2 1 0 0
Insects ~1 ~1 0 0.5 - ~1 0.5 - 1
Diseases 5 1 1 0.5 0.5
Other factors* 9 0 0 0 16
*Other factors indicated was market conditions


Table 3. Insect pest infestations in melons
  Spring cantaloupe Fall cantaloupe Spring honeydew Fall honeydew Seedless watermelon Seeded watermelon
Percentage of acres treated for insects 100 100 100 100 100 100
Percentage of acres treated for insects at planting 100 100 100 100 100 100
Percentage of acres treated for insects by foliar application 24 100 13 100 95 100
Percentage infested by ground dwelling insects 65 48 30 24 38 74
Percentage of acres treated for this pest 65 48 30 24 38 74
Number of pesticide applications required to control this pest 1 - 5

0 - 5

1 - 5 0 - 5 0 - 2 0 - 2
Percent reduction in yield due to this pest 0 - 2 0 0 0 0 0
Percentage of acres infested by whiteflies 39 100 13 100 95 100
Percentage of acres treated for this pest 24 100 13 100 76 64
Number of pesticide applications required to control this pest 0 - 1 3 - 4 1 1 - 4 1 1
Percent reduction in yield due to this pest 0 0 0 0 ~1%

0

Percentage of acres infested by cabbage loopers 22 24 8 41 40 45
Percentage of acres treated for this pest 17 24 8 41 30 26
Number of pesticide applications required to control this pest 0 - 1 0 - 2 0 - 1 0 - 2 0 - 1 0 - 1
Percent reduction in yield due to this pest ~1%

0

~1%

0

~1%

~1%

Percentage of acres infested by spider mites 2 3 0 0 38 74
Percentage of acres treated for this pest 0 0 0 0 38 74
Number of pesticide applications required to control this pest 0 0 0 0 0 - 1 0 - 1
Percent reduction in yield due to this pest 0 0 0 0 0.50% 0.50%
Percentage of acres infested by beet armyworm 0 0 0 0 4 7
Percentage of acres treated for this pest 0 0 0 0 0 0
Number of pesticide applications required to control this pest 0 0 0 0 0 0
Percent reduction in yield due to this pest 0 0 0 0 0 0
Percentage of acres infested by leafminers 5 57 0 28 0 0
Percentage of acres treated for this pest 0 57 0 28 0 0
Number of pesticide applications required to control this pest 0 0 - 2 0 0 - 2 0 0
Percent reduction in yield due to this pest 0 0 0 0 0 0
Percentage of acres infested by aphids 0 0 0 0 0 0
Percentage of acres treated for this pest 0 0 0 0 0 0
Number of pesticide applications required to control this pest 0 0 0 0 0 0
Percent reduction in yield due to this pest 0 0 0 0 0 0


Table. 4 Disease incidence in melons
  Spring Cantaloupe Fall Cantaloupe Spring Honeydew Fall Honeydew Seedless Watermelon Seeded Watermelon
Percentage of acres treated for diseases 42 100 100 100 95 100
Percentage of acres treated for diseases at planting 0 90 0 0 0 0
Percentage of acres treated for diseases by foliar application 42 100 100 100 58 50
Percentage of acres infected by unidentified soil-borne diseases 0 90 0 0 0 0
Percentage of acres treated for this disease 0 0 0 0 0 0
Number of pesticide applications required to control this disease 0 0 0 0 0 0
Percent reduction in yield due to this disease 0 0 0 0 0 0
Percentage of acres infected by seedling soil-borne diseases 0 0 0 0 0 0
Percentage r of acres treated for this disease 0 0 0 0 0 0
Number of pesticide applications required to control this disease 0 0 0 0 0 0
Percent reduction in yield due to this disease 0 0 0 0 0 0
Percentage of acres infected by vine decline soil-borne diseases 4 0 0 0 20 77
Percentage of acres treated for this disease 0 0 0 0 0 0
Number of pesticide applications required to control this disease 0 0 0 0 0 0
Percent reduction in yield due to this disease 1% 0 0 0 0.50% 0.50%
Percentage of acres infected by powdery mildew 42 100 100 100 58 50
Percentage of acres treated for this disease 42 100 100 100 58 50
Number of pesticide applications required to control this disease 1 2 - 3 1 2 1 - 2 2
Percent reduction in yield due to this disease 4% 1% 0 1% 0 0
Percentage of acres infected by other foliar diseases 0 33 0 41 0 0
Percentage of acres treated for this disease 0 33 0 41 0 0
Number of pesticide applications required to control this disease 0 1 0 1 0 0
Percent reduction in yield due to this disease 0 0 0 0 0 0
Percentage of acres infected by viruses 0 0 0 0 0 0
Percent reduction in yield due to this disease 0 0 0 0 0 0


Table. 5 Weed incidence in melons
  Spring Cantaloupe Fall Cantaloupe Spring Honeydew Fall Honeydew Seedless Watermelon Seeded Watermelon
Percentage of acres treated for weeds 82 90 95 96 42 74
Percentage of acres treated for weeds at planting 82 90 95 96 42 74
Percentage of acres treated for weeds by foliar application 21 14 27 21 0 0
Percentage of acres infested by annual grass weeds 20 0 2 0 38 74
Percentage of acres infested by perennial grass weeds 15 14 19 21 0 0
Percentage of acres treated for grass weeds at planting 24 14 16 0 38 74
Percentage of acres treated for grass weeds postemergence 15 14 19 21 0 0
Percent reduction in yield due to annual grass weeds 0 0 0 0 0 0
Percent reduction in yield due to perennial grass weeds 0 0 0 0 0 0
Percentage of acres infested by pigweeds 24 0 8 0 38 74
Percent reduction in yield due to pigweeds 0 0 0 0 0 0
Percentage of acres infested by nutsedge 9 14 0 0 8 15
Percent reduction in yield due to nutsedge 0 2% 0 0 0 0
Percentage of acres infested by groundcherry 18 0 0 0 38 74
Percent reduction in yield due to groundcherry 0 0 0 0 0 0
Percentage of acres infested by purslane 24 0 8 0 38 74
Percent reduction in yield due to purslane 0 0 0 0 0 0
Percentage of acres infested by other broadleaved weeds 18 0 0 0 38 74
Percentage of acres treated for broadleaved weeds at planting 24 14 16 0 38 74
Percent reduction in yield due to other broadleaved weeds 0 0 0 0 0 0

Full Disclaimers

Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director Cooperative Extension, College of Agriculture and Life Sciences, The University of Arizona.

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Information provided by:
Kai Umeda, kumeda@ag.arizona.edu Area Extension Agent, Vegetable Crops
University of Arizona, Tucson, Arizona.
Material written 2003.

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