Research Program on
Pumpkin Diseases in Illinois
M. Babadoost,
S.Z. Islam, D. Tian, C. Pavon and M. Hurt, Department of Crop Sciences, University
of Illinois, Urbana-Champaign; J.M.
Swiader and H.M. Fouly,
Department of NRES, University of Illinois, Urbana-Champaign; M.O. Ogutu, Extension Service,
University of Illinois, 6438 Joliet Rd., Countryside, IL; S.A. Walters; Department of Plant, Soil, and General Agriculture, Southern
Illinois University, Carbondale, and Y.
Honda, Faculty of Life and Environmental Science, Shimane University,
Matsue, Japan.
Illinois ranks first in
pumpkin production in the nation.
Approximately, 12,000 acres of jack-o-lantern and 9,000 to 10,000 acres
of processing pumpkins are produced in Illinois. About 90% of processing
pumpkins produced in the United States are grown in Illinois. Several diseases,
including powdery mildew (Sphaerotheca
fuliginea), Phytophthora blight (Phytophthora
capsici), downy mildew (Pseudoperonospora
cubensis), gummy stem blight and black rot (Didymella bryoniae), Plectosporium blight (Microdochium blight) (Plectosporium tabacinum), Fusarium wilt
and fruit rot (Fusarium spp.), Sclerotinia
rot (Sclerotinia sclerotiorum), bacterial
spot (Xanthomonas campestris pv. cucurbitae), bacterial wilt (Erwinia tracheiphila), and virus
diseases including cucumber mosaic virus (CMV), squash mosaic virus (SqMV), watermelon
mosaic virus (WMV), zucchini yellow mosaic virus (ZYMV), and papaya rings spot
virus (PRSV) occur in pumpkin fields in
Illinois, causing up to 100% yield losses. A research program was initiated in
2000 to develop effective methods for management of diseases of jack-o-lantern
and processing pumpkins in Illinois. The objectives of this research program are:
(i) to evaluate effectiveness of fungicide seed-treatment on controlling
seedling death of pumpkins caused by P.
capsici in pumpkin fields; (ii) to evaluate effectiveness of fungicide
spray application on controlling foliar blight and fruit rot of pumpkins; (iii) to determine the effectiveness of
induced plant resistance by red-light treatment on controlling foliar blight
and fruit rot caused P. capsici and
other diseases of pumpkins; (iv) to assess the effectiveness of calcium
application on suppressing P. capsici
in the field; and (v) to evaluate the effectiveness of integrated approaches of
seed treatment, fungicide spray, red-light treatment and calcium application on
controlling pumpkin diseases.
The research on management of
pumpkin diseases is funded by: Department of Crop Sciences-University of
Illinois, Illinois Department of Agriculture, North Central-IPM Program, North
Central Region-SARE, Nestle Food Company, BASF Corp., Bayer Corp., Cerexagri
Inc., DuPont Corp., Syngenta, and Uniroyal Chemical Co.
This research program has already
offered effective control of several pumpkin diseases, especially control of the
devastating disease caused by P. capsici.
This research also has resulted in publishing several papers in peer-reviewed
journals, Extension Newsletters, and Websites. The following are some of these
publications.
1. Babadoost,
M.
2000. Outbreak of Phytophthora
foliar blight and fruit rot in processing pumpkin fields in Illinois. Plant Dis. 84:1345.
2.
Islam, S.Z., Babadoost,
M., and Honda, T. 2002. Effect of
red-light treatment of seedlings of pepper, pumpkin, and tomato on the
occurrence of Phytophthora damping-off. HortScience 37: 678-681.
3.
Islam, S.Z., Honda, Y.,
Babadoost, M. 2002. Antifungal glycoprotein in red-light irradiated broadbean
leaflets. Mycoscience 43:471-473.
4.
Babadoost, M., and
Islam, S. Z. 2002. Phytophthora blight on pumpkin. Plant Health Progress
doi:10.1094/PHP-2002-1216-01-DG.
5.
Babadoost, M., and
Islam, S.Z. 2003. Fungicide seed
treatment effects on seedling damping-off of pumpkin caused by Phytophthora
capsici. Plant Dis. 87:63-68.
6.
Islam, S.Z., and Babadoost, M. 2003. Genetic
and pathogenic variation among Phytophthora capsici isolates infecting
processing pumpkin. Plant Dis. 87 (submitted).
7.
Tian, D., and Babadoost, M. 2003. Host range
of Phytophthora capsici from pumpkin and pathogenicity of the isolates.
Plant Dis. 87 (submitted).
8.
Babadoost, M. 2000. Incidence and impact of Phytophthora
diseases. Illinois State Hort. Soc. Summer Orchard Day 2000: 22-25.
9.
Babadoost, M., and
Islam, S.Z. 2001. Studies on chemical control of Phytophthora blight of
processing pumpkins. 2001 Processing
Crops Manual and Proc. Midwest Food Processors Assoc. 2001: 69-177.
10.
Babadoost, M. 2002.
Evaluation of selected fungicides to control jack-o-lantern pumpkin diseases.
2002 Processing Crops Manual and Proc. Midwest Food Processors Assoc.
2002:145-251.
11.
Babadoost, M. 2002.
Cucurbit and cucurbit diseases in Illinois. The 46th Ann. Agronomy
Day, UI 2002: 39.
12.
Babadoost, M. 2002.
Management of Phytophthora blight of cucurbit crops in Illinois. Cucurbitaceae
2002, Phytophthora capsici
Symposium:31-32. Naples, FL.
13.
Babadoost, M., and Islam, S.Z.
2001. Evaluation of fungicides for control of Phytophthora blight of
processing pumpkin, 2000. Fung. & Nemat. Tests 56:V65.
14.
Babadoost, M. 2001.
Phytophthora Blight of Cucurbits (Fact Sheet, RPD), 3 pp. http://www.aces.uiuc.edu/vista/abstracts/a945.html.
15.
Babadoost, M. 2002.
Website: http://veg-fruit.cropsci.uiuc.edu.
Research
Projects on Management of Pumpkin Diseases
I. Control
of Phytophthora Blight of Pumpkins by Fungicide Spray
M. Babadoost and S. Z. Islam, Department of Crop
Sciences, University of Illinois, Urbana-Champaign.
Prior to 2001, there was no
method available to provide adequate control of P. capsici in pumpkin fields in Illinois. The common practice for
reducing the incidence of this disease in vegetable fields has been an
integrated approach combining long-term crop rotation, sanitation, and
management of field moisture. This
approach does not provide adequate protection to crops against P. capsici because: (i) the pathogen
survives in the soil indefinitely, and (ii) in the areas with high relative
humidity and/or rainfall, management of field moisture is not feasible. No
resistant pumpkin variety is available. Other practices including amending
soil, using cover crops, straw mulching, soil solarization, and using
antagonistic fungi for protecting crops in the fields have been investigated,
but none of them have provided adequate protection in cucurbits against P. capsici. In some areas, fungicides
have been used to reduce the incidence of Phytophthora diseases of vegetables.
During 2000-2001, we tested
more than 30 fungicides with potential effect on Phytophthora species to evaluate their effectiveness on controlling
P. capsici on pumpkins. Extensive
tests were carried out in the laboratory, greenhouse, and fields. As a result,
we recommended using dimethomorph (Acrobat) for controlling foliar blight and
fruit rot of pumpkins caused by P.
capsici. We obtained permission
from USEPA under section 18 permission of FIFRA for the use of dimethomorph
(Acrobat) for foliar spray to control foliage blight and fruit rot caused by P. capsici in cucurbit fields in 2001
and 2002. In the fall of 2002, this compound was registered for the use on
cucurbit crops. However, only five spray applications of Acrobat are permitted
during a growing season. Thus, this approach was a short-term solution for
saving pumpkin industry from the devastating Phytophthora disease. There is
definitely an urgent need for development of long-term strategies for
management of Phytophthora diseases in pumpkins, as well as other vegetables,
in Illinois.
Five applications of dimethomorph (6.4 oz Acrobat
50WP/acre) plus copper sulfate (2.5 lb Cuprofix Disperss/acre), at a weekly
schedule, provide effective protection against foliar blight and fruit rot,
caused by P. capsici, in pumpkin fields. Application of the fungicides
begins at the first sign of the disease. In 2002, fungicide spray reduced yield
losses from 100% to less than 10% in the commercial fields.
II. Fungicide Seed Treatment
Effects on Seedling Damping-Off of Pumpkin Caused by Phytophthora capsici.
M. Babadoost and S.Z. Islam, Depart. of Crop Sciences,
Univ. of Illinois, Urbana-Champaign.
Phytophthora blight, caused by the Oomycete plant
pathogen Phytophthora capsici, is an
important disease of cucurbits, eggplants, peppers, and tomatoes. The incidence
of this disease has increased in recent years in the United States and
worldwide. P. capsici survives as
oospores in soil and as mycelium in plant residue. The pathogen can infect all
parts of the plant at any growth stage, causing pre- and post-emergence seeding
damping-off, leaf spot, stem lesion, foliar blight, and fruit rot. No cucurbit cultivar with measurable
resistance against Phytophthora blight is available. The objective of this study
was to develop a fungicide seed-treatment for control of seedling death of
pumpkins caused by P. capsici.
Seed treatment with mefenoxam
(0.65 fl oz Apron XL LS/100 lb seed) and metalaxyl (1.5 fl oz Allegiance FL/100 lb seed) significantly
reduced pre- and post-emergence damping-off of seedlings caused by P. capsici in three pumpkin cultivars,
Dickinson, Hybrid-401, and Hybrid-698, tested. Thirty-one days after seeding,
at inoculum levels of 0, 90, 600, 1400, and 4000 cfu/g soil, the average
seedling stands for Apron treatment were 98.4,
93.8, 88.3, 77.8, and 64.8%; for Allegiance, were 99.1,
85.3, 85.8, 73.5, and 59.3; and for the untreated control were 97.5, 55.2, 45.7, 37.0, and 22.9%, respectively. In field trials, the average seedling stands 35 days after
seeding were 76.7, 74.7, and 44.9% for Apron, Allegiance, and untreated control, respectively. Seed treatment with Apron
or Allegiance did not have any significant effect on
either seed germination or seedling vigor. The integration of seed treatment
with Apron or Allegiance with foliar spray of plants with Acrobat provides satisfactory
protection of pumpkin plants against P.
capsici during the 4-month growing season.
III. Effect of Red-Light Treatment
of Seedlings of Pumpkin, Pepper, and Tomato on the Occurrence of Phytophthora
Damping-off
S. Z. Islam and M. Babadoost, Department of Crop Sciences, University of Illinois,
Urbana-Champaign; and Y. Honda, Faculty
of Life and Environmental Science, Shimane University, Matsue, Japan.
A study was conducted in the
greenhouse to investigate the effects of red light (600-700 nm) on the
subsequent occurrence of seedling infection of bell pepper, pumpkin, and tomato
caused by Phytophthora capsici.
Three- or four-week-old seedlings were inoculated with zoospores or
transplanted into pots filled with artificially infested soil mix. Red-light treatment of seedlings
reduced Phytophthora damping-off by up to 79%. Only 21 to 36% of red light
treated seedlings became infected, whereas 78 to100% of the control seedlings,
grown either in natural daylight (NDL) or under white light (WL), became
infected and died. The height, fresh and dry weight of seedlings treated with
red light were significantly higher than those grown under NDL or WL.
IV. Determining Host Range of Phytophthora capsici from Pumpkin and
Pathogenicity of Isolates
D. Tian, and M. Babadoost; Depart. of Crop Sciences, Univ. of Illinois, Urbana-Champaign
This study was conducted to
determine host range of Phytophthora
capsici isolates from pumpkin and virulence of the isolates on pumpkin
cultivars. The pathogenicity of P.
capsici isolates from pumpkin was evaluated on 45 species of herbaceous
plants, including 36 species of crops grown in rotation sequences with pumpkin
and nine species of weeds that commonly grow in pumpkin fields in Illinois.
Plants were grown in the greenhouse and 4-wk-old seedlings were inoculated by
adding 5 ml of a zoospore suspension (2 x 105 spores/ml of water)
onto soil surface around stem of each plant in the pot. Twenty-two crop species
and two weed species became infected with P.
capsici and developed symptoms. Phytophthora
capsici was re-isolated from all of the symptomatic plants by culturing
tissues on a semi-selective medium (PARP). Also, P. capsici was detected in 87.5% of infected plants by a PCR method
using PCAP and ITS5 primers. Cucurbits and peppers were the most susceptible
hosts of P. capsici. Five crop
species/variety, beet (Beta vulgaris),
Swiss chard (Beta vulgaris var. cicla), lima beans (Phaseolus lunatus), turnip (Brassica
rapa), and spinach (Spinacia olerace),
and one weed species, velvet leaf (Abutilon
theophrasti), were found hosts of P.
capsici for the first time. Six isolates of P. capsici were inoculated onto six pumpkin cultivars (three
processing and three jack-o-lantern pumpkins) in the greenhouse and found
significantly isolate × cultivar interactions. Phytophthora capsici isolates were more virulent on jack-o-lantern
pumpkins than processing pumpkins.
V. Pathogenic Variation in Phytophthora capsici Isolates from
Processing Pumpkin in Illinois
S.Z. Islam, M. Babadoost, and K. Lambert, Department of Crop Sciences, University of Illinois,
Urbana-Champaign; H.M. Fouly, Department of Natural Resources and
Environmental Sciences, University of Illinois, Urbana-Champaign.
This study investigated
genetic, pathogenic, and morphological variation among Phytophthora capsici isolates from processing pumpkin in Illinois.
Random amplified polymorphic DNA (RAPD) markers were employed to assess genetic
variation among 15 isolates of P. capsici
from 15 individual fields at five locations. Unweighted mean pair group
analysis clustered isolates into five groups. The genetic distances ranged from
0.17 to 0.36. Inoculation of pumpkin seedlings in the greenhouse revealed that
isolates belonging to distinct genetic groups differed significantly (P = 0.05) in aggressiveness. Isolates of
P. capsici tested exhibited four
growth patterns: cottony, rosaceous, petaloid, and stellate. Isolates of P. capsici, including an ATCC isolate (ATCC-15427), having cottony
growth pattern could not grow at 36°C. The mean
oospore diameter in A1 mating type isolates was greater than that of A2 mating
types. Five of 20 isolates tested produced chlamydospores in V8-CaCO3 liquid
medium. This is the first report of chlamydospore formation of cucurbit
isolates of P. capsici.
VI. Pathogenic
and Genetic Variation of Phytophthora
capsici isolates from Illinois
D. Tian, and
M. Babadoost; Depart.of Crop
Sciences, Univ. of Illinois, Urbana-Champaign.
The objective of this study was
to investigate genetic and pathogenic variation among P. capsici isolates from Illinois. Phytophthora capsici
isolates were collected from various hosts and locations in Illinois. The rate
of colony growth, morphology of sporangia, and pathogenicity of the isolates
were investigated. There were significant differences in the rate of colony
growth among the isolates. Also, length, breath, length/breath ratio, and
length of pedicels of sporangia of the isolates differed significantly.
Pathogenicity test in the greenhouse showed that P. capsici isolates from pumpkin were significantly less aggressive
on eggplant than they were on cucurbits, pepper, and tomato. Three
pathogenicity groups were determined among the isolates from different
locations. No significant relationship between pathogenicity of the isolates
and original hosts was found. Genetic variation among the isolates was studied
using internal transcribed spacer (ITS) regions of rDNA, inter simple sequence
repeat (ISSR), and amplified fragment length polymorphism (AFLP) methods. No
significant difference was detected in ITS regions of the isolates. ISSR and
AFLP tests showed genetic variation among the isolates. Cluster analysis
separated the isolates into three distinct groups, based on the locations that
they had been collected. It was concluded that isolates of P. capsici from different regions of the state differ in genetic
combination and virulence.
VII. Integrated
Management of Pumpkin Diseases
M. Babadoost, S.Z. Islam, and M. Hurt Department
of Crop Sciences, University of Illinois, Urbana-Champaign; J.M. Swiader, Department of NRES,
University of Illinois, Urbana-Champaign; M.O.
Ogutu, Extension Service, University of Illinois, 6438 Joliet Rd., Countryside,
IL; and S.A.
Walters, Department of Plant, Soil, and General Agriculture, Southern
Illinois University, Carbondale.
A research study is underway
in a commercial pumpkin field at Pekin, IL, to determine the most effective
integrated management of pumpkin diseases. Integrated approaches of seed
treatment, fungicide spray (11 fungicides), calcium application (soil and
plant), and using induced plant resistance (red light and chemical) on
controlling pumpkin diseases (with emphasis on Phytophthora blight) are being
investigated. The trial includes 30 treatments arranged in a completely
randomized block design with 3 replications. Weekly data on the incidence and
severity of diseases are collected and the results will be available at the end
of the season.
VIII. Evaluating Efficacy of Selected Fungicides on
Controlling Jack-O-Lantern Pumpkin Diseases, Champaign, IL
M. Babadoost and M. Hurt Depart. of Crop Sciences, Univ.
of Illinois, Urbana-Champaign
In 2003, a field trial is
being conducted at the University of Illinois Vegetable Research Farm at
Champaign, IL, to evaluate the efficacy of selected fungicides on controlling
diseases of jack-o-lantern pumpkin.