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j i)

AGRICULTURAL RESEARCH & EDUCATION CENTER
S- IFAS, University of Florida
^X-ri Bradenton, Florida
/ H l.iUML LIB;ARYi
Bradenton AREC Research Report GC1982-3 February, 1 82

WEED SURVEY OF VEGETABLE AND ORNAMENTAL ROWER'Ph SOU~AlLORIDA

J. P. Gilreath I.F.A.S. Univ. of Florida

A weed survey was conducted in the spring of 1981 by mailing out a questionnaire
designed to determine the most troublesome weeds in the principal crops of the area.
This survey was conducted with the cooperation of the vegetable and ornamental
extension agents of Manatee, Sarasota, Hillsborough, Pinellas, Sumter, and Martin
Counties. The questionnaire was sent by extension agents in the respective counties
to the growers on their mailing lists.

Overall response to the survey was quite poor with a 4% response being the
best (Table 1). It was interesting to note that the highest percentage response
was from those counties immediately surrounding the Bradenton Agricultural Research
and Education Center. This suggests the regional influence an AREC has on the growers
it serves.

Table 2 presents a listing of the major crops grown by the respondents and the
principal weeds in those crops and the major herbicides used. The ranking of weeds
and herbicides was based on an average weighted for acreage. That is, if pigweed
was reported by 2 growers with a total of 00 acres and nightshade was reported by
6 growers with a total of 100 acres, pigweed outranked nightshade as a weed pest.
The most important general categories of vegetables and ornamentals are listed
in Tables 3 and 4. Ranking for weeds in vegetables varies somewhat from those for
specific crops due to information on the many minor crops. Overall, purple nutsedge,
Cyperus rotundus, was the worst weed in all crops followed by perennial and annual
grasses.

Table 1. Response to weed questionnaire
Response by county as
percent of total no. of
No. forms No. responses % of Questionnaires
County mailed received county mailed out Responses

Manatee 300 12 4.0 0.7 33.3
Sarasota 276 11 4.0 0.6 30.6
Hillsborough 590 5 0.9 0.3 13.9
Martin 159 4 2.5 0.2 11.1

Pinellas 500 4 0.8 0.2 11.1
Sumter* 1 N/A N/A N/A
*Information from Extension Agent.

Table 2. List of important weeds and 1ost commonly used herbicides by crop.

Rank Heed Rank Herbicide

Tomato
Purple nutsedge (Cyperus rotundus)
Pigweed (mainly Amaranthus viridis)
Nightshade (Solanum nigrum)
Lambsquarter (Chenopodium album)
Purslane (Portulaca oleracea)

Paraquat
Sencor

Pepper

Purple nutsedge (Cyperus rotundus)
Pigweed (mainly Amaranthus viridis)
Purslane (Portulaca oleracea)
Sesbania (Sesbania macrocarpa)
Bermudagrass (Cynodon dactylon)

Watermelon
Purple nutsedge (Cyperus rotundus)
Pigweed (mainly \;laaranthus viridis)
Purslane (Portulaca oleracea)
Bermudagrass (Cynodon dactylon)
Sesbania (Sesbania macrocarpa)

Cucumber
Same as for watermelon

Strawberry
Hairy indigo (Indigofera hirsuta)
Coffeebean (Cassia occidentalis)
Clover (Trifolium repensT)

Dymid, Treflan
Devrinol

Alanap
Treflan

Dymid
Treflan

Paraquat
Devrinol
Lasso

Woody Ornamentals
Field Grown

Purple nutsedge (Cyperus rotundus)
Bermudagrass (Cynodon dactylon)
Dogfennel (Eupatorium capillifolium)
Crabgrass (Digitaria ciliaris)
Goosegrass (Eleusine indica)

Treflan
Ronstar G
Round-up

Container Grown

Purple nutsedge (Cyperus rotundus)
Oxalis (Oxalis sp.)
Spurge (Euphorbia sp.)
Goosegrass (Eleusine indica)
Crabgrass (Diqitaria ciliaris)

Ronstar G
Round-up

Table 2. (continued)

[iums

Grass
Droadleaf

Greenhouse Ornamentals

Oxalis (Oxalis sp.)
Artillery fern (Pilea microphylla)

Ho Herbicides
Hand weeding

Turf

Purple nutsedge (Cyperus rotundus)
Bermudagrass (Cynodon dactylon)
Crabgrass (Digitaria ciliaris)
Goosegrass (Eleusine indica)
Crowfoot grass (Dactyloctenium aegjyptium)

MSfPU\
Atrazine
Ronstar
Kerb
Balan

Citrus

Bermudagrass (Cynodon dactylon)
Morning glory (Ipomoea sp.)
Virginia creeper (Parthenocissus quinquefolia)
Dogfennel (Eupatorium capillifolium)

Hyvar
Paraquat
Krovar

*
Table 3. Ten most important weeds in vegetables based on growers' responses.

Rank Common Name Genus-species Key crops

Purple nutsedge
Pi gweed

Lan:bsquarters
Purslane

Bermudagrass
Iightshade
Hemp sesbania
lhite clover

Crabgrass
Dogfennel

Cyperus rotundus
Amaranthus viridis
(mainly)
Chenopodium album
Portulaca oleracea

Cynodon dactylon
Solanum nigrum
Sesbania macrocarpa
Trifolium repens

Digitaria ciliaris
Eupatorium capillifolium

All vegetables

All vegetables
Tomatoes and peppers
Tomatoes, peppers, watermelon,
cucumber, sweet corn, misc.
All vegetables (esp. vine crops)
Tomatoes, peppers
All vegetables
Tomato, pepper, melons,
cucumber, strawberries
All vegetables
Tomatoes

Ranking based on average frequency weighted for acreage involved

Table 4. Five most important weeds in ornamentals based on growers' responses.

Rank Connon !ame Genus-species

1 Purple nutsedge Cyperus rotundus
2 Bermudagrass Cynodon dactylon
3 Crabgrass Diqitaria ciliaris
4 Goosegrass Eleusine indica
5 Oxalis Oxalis sp.

1 Paraquat