A Plain Language Guide Growing Fresh Market Pumpkins ... · A Plain Language Guide Growing Fresh Market Pumpkins, Squash, and Gourds A. C. Newenhouse. The Wisconsin Farm Center has

A Plain Language Guide

GrowingFresh MarketPumpkins,

Squash,and Gourds

A. C. Newenhouse

�The Wisconsin Farm Center has more informationabout services to help beginning farmers. To find this information on the internet look under the heading Farming and Agriculture athttp://datcp.state.wi.us/.

Your local county Extension office also has moreinformation for fresh market farmers. Go to http://www.csrees.usda.gov/Extension/. Click on your state and then your county to findthe Extension office near you.

Plant Description ..............................................................................1

Site Selection ....................................................................................3Table A. Cucurbita species........................................................................................3

Variety Selection................................................................................4

Planting and Care ..............................................................................5Starting Seeds ..........................................................................................................5Frost dates map ........................................................................................................5These are the steps to start seeds indoors:..............................................................7Table B. Planting guide..............................................................................................8

Soil preparation ................................................................................9Raised beds ..............................................................................................................9Season extenders ....................................................................................................9

Soils and Nutrient Management ....................................................11Soil pH ....................................................................................................................11Fertilizer needs ......................................................................................................11Table C. Annual nitrogen, phosphate, and potash for pumpkins, squash, and gourds ..11

Irrigation ..........................................................................................12

Weed Management ..........................................................................13

Harvest, Handling, and Storage......................................................14

Preventing Stress on Your Body ....................................................16

Pest and Disease Management........................................................17Diseases ................................................................................................................17Downy mildew ........................................................................................................18Powdery mildew......................................................................................................18Black rot ..................................................................................................................19Bacterial wilt............................................................................................................20Viruses....................................................................................................................21

Insect Management..........................................................................22Squash vine borer ..................................................................................................22Squash bug ............................................................................................................23Striped and spotted cucumber beetles ..................................................................24

Indexi

Pumpkins, squash and gourds aregood crops to grow for the farmersmarket because many people want tobuy them in the fall. Pumpkins andsquash are used as decorations andalso eaten. Gourds are used only asdecorations, not food. If you have afarm and want customers to come toyou, it is a good idea to grow and sellpumpkins. Pumpkins,squash andgourds grow on vines that cover theground. If you have a field that has alot of weeds, you can grow pumpkins,squash, and gourds to help clean upthe field.

Plant DescriptionPumpkins, squash, and gourds are allmembers of the Cucurbit family.Cucurbits are native to North andSouth America. Most pumpkins,squash, and gourds belong to one ofthree species of Cucurbits: Cucurbitapepo, Cucurbita maxima, or Cucurbitamoschata. A plant called ‘pumpkin’can be either Cucurbita pepo,Cucurbita maxima, or Cucurbita

moschata. Each species is a littledifferent from the others. Table A liststhe plants, their species, and thecountries where the plants are native.

Pumpkins, squash, and gourds arewarm season annual crops. Theyhave two types of growth pattern. Oneis called determinate. Determinateplants form flowers and fruit at theend of shoots. Plants are upright andbushy. Another type is calledindeterminate. Indeterminate plantsform flowers and fruit at the pointwhere a leaf grows out from the stem.The shoots keep growing. Plants growflat on the ground and form vines.Most of the plants in the Cucurbitafamily form short twisted branchescalled tendrils. Tendrils wrap aroundstems or stakes as the plant grows.

Pumpkins, squash, and gourds haveshallow roots that grow in a widearea. Roots can grow along a vine asit lies on the ground. Roots form onthe stem at the place where a leafgrows.

1Plant Description

IndeterminateDeterminate

Howard F. Schwartz, Colorado State University,Bugwood.org


Pumpkins, squash, and gourds havetwo kinds of flowers on each plant.One type is the male flower and theother type is the female flower. Onlythe female flower will form a fruit.Male flowers makepollen for femaleflowers. The twokinds of flowers havethese differences:

Male flowers�

have a stamen

Male flowers do�

not form fruit.

Male flowers�

have a longthin flowerstalk.

Female flowers�

have a pistil

A tiny fruit forms�

below thefemale flower.

Female flowers�

have a shortflower stalk.

Flowers are only open for one day,typically in early morning. Insectscarry pollen to pollinate pumpkins,squash and gourds. Flowers needmany bee visits to get enough pollento set fruit. If a flower does not getenough pollen it will not set fruit. If aflower gets more pollen it will makebigger fruit.

You will need 1-2 bee hives per acrefor a good crop of pumpkins, squashand gourds. Bees do not like to fly inwind, rain, or cold. If this weatherhappens you will get poor pollination.If you do not have good pollination,you will not get many fruit. Also, fruitwill have poor shape.

If you have a field with different kindsof pumpkins, squash, and gourds,bees can carry pollen from one kindof plant to the flowers of another. Thefruit that grows will not look different.If you save the seeds from that fruitand plant them, the new fruit mightlook like a mix of the parents.

2Plant D

escription

Site SelectionPumpkins, squash, and gourds needfull sun, heat, and a long growingseason. Choose well drained soilsthat warm quickly. Soil that are poorlydrained do not warm up as fast inspring. Light, sandy soil is best.

Soils that have a lot of organic matter,such as muck soil or peat soil, are notgood for pumpkins, squash andgourds. Fruit grown on these soils willbe soft and not as sweet.

The best soil pH for pumpkins,squash and gourds is 6.0-6.8.

3Site Selection

Table A. Cucurbita speciesSpecies Plants Native country Type of pumpkin

Cucurbita pepo Pumpkin, acorn squash,summer squash, zucchini,spaghetti squash, delicatasquash, small gourds

United States ,Mexico

- Bright orange skin

- Hard, woody, stemwith ridges

Cucurbita maxima Very large pumpkins, wintersquash, buttercup squash,hubbard squash, turbansquash, banana squash, largegourds

Chile, Argentina,Bolivia, Uruguay

- Yellow skin

- Soft stem like asponge or cork

Cucurbita moschata Pumpkin, winter squash,butternut squash

Mexico, Peru - Long, not round

- Tan skin

- Stem has ridges

Variety SelectionChoose varieties that resist disease.You can grow pumpkins that aremeant for eating or pumpkins meantfor decoration. Pumpkins meant foreating are sometimes called piepumpkins. Pumpkins come in a lot ofdifferent colors, types, and sizes.

Squash varieties are either “summersquash” or “winter squash”. Summersquash has thin skin and is ready inmid summer. Winter squash has thickskin, is ready late in the season, andkeeps well. There are many flavors,shapes, colors, and sizes of squash.

There are always new varieties ofpumpkins and squash for decoration.Some growers like to have the newestor most unusual varieties for theircustomers.

4Variety S

election

Planting and CarePumpkins, squash, and gourds dobest when grown from seeds planteddirectly into the field. It is not easy totransplant pumpkins, squash andgourds because they do not do wellwhen their roots are disturbed. Vinecrops need a lot of space to grow,especially the indeterminate types ofplants and the larger pumpkinvarieties.

Starting SeedsIf the growing season is too short andyou have to start the seeds in agreenhouse or under lights, plantthem inside 3-4 weeks before they goin the field. Plant in the field after thelast frost date in your area (see frostdate map).

You can buy or mix your own sterilepotting mix. The mix should includecompost, peat, or sphagnum to holdmoisture; vermiculite or perlite foraeration; and mineral and nutrient

5Planting and Care

April 26 - May 2

May 3 - 9

May 10 - 16

May 17 - 23

May 24 - 30

May 31- June 6

September 13 - 19

September 20 - 26

September 27 - October 3

October 4 - 10

October 11-17

October 18 - 24

Frost dates mapLast spring killing frost First fall killing frost

sources to feed the new plants afterthe first roots form. Add water to makethe mix moist before you fill thetransplanting trays.

Since vine crops do not transplanteasily, try to protect the roots as muchas you can. Farmers plant seeds intoeither paper or peat pots that can beplanted. Or use a paper or fiber potthat you can peel away before youplant. If you use a plastic pot or cell

pack, the shape should be tapered soit is easy to pull the plant out of thepot. Sterilize the plastic pots in a 10%bleach solution before you plant. Thiswill prevent bacteria and fungi frominfecting the young seedlings. Pots orcells should be 2” in diameter.

Make a 10% bleach solution byputting 1 part bleach into 9 partswater. For example, mix 1 cup bleachwith 9 cups water.

6Planting and C

are

These are the steps to startseeds indoors:

Fill the pots with potting soil. �

Plant seeds ½-1 inch deep. Plant�

two or three seeds per cell.

Label the pots with variety and�

planting date.

Keep soil moist but not wet. �

Use a heating mat or cable�

under the pots to keep the soilwarm to 70°F until the seedlingssprout. You should seeseedlings sprouting in 10 days.

The temperature in the�

greenhouse should be 70-75°Fduring the day.

The temperature in the�

greenhouse should be 60-62°Fduring the night.

As plants grow, thin them so only�

1-2 plants are in each cell. Usea scissors to clip out unwantedplants. This way the roots willnot be disturbed.

Four to seven days before�

transplanting out to the field,harden off the plants by puttingthem outside for a few hourseach day during the warmesttime of the day, or move plantsinto a cold frame. Cold framesare a type of planting bed madeby building wooden sides oneach side of a bed on theground. The back is higher thanthe front and the frame holds upa glass top at an angle to thesun facing south. You can usean old window to make a coldframe.

If the temperature will go below�

45°F, bring plants inside.

Give the plants less water and�

no fertilizer while they arehardening off.

Plant seeds or transplants in the fieldafter the last spring frost and whenthe soil temperature is at least 60°F.These crops grow best attemperatures of 65-75°F at night and75-86°F daytime. Seeds sproutfastest at 85°F soil temperature.

Pumpkins, squash and gourds areusually planted by seed into the field.Look at table B for the amount ofseed you will need, how deep to plantseed, how far apart to plant, when toplant, days to first harvest, and yield.Seeds are planted in rows or in hills.Hills are small mounds with 3-5 seedsin them. If you plant in hills, thin theseedlings to 1-3 plants per hill.

7Planting and Care


Some farmers use a small machinecalled a walk-behind plate seeder toplant seeds. If the soil is too cold (lessthan 60°F) or too wet, seeds will rot.Plant seeds 1-1.5 inches deep.

If you plant transplants, look at TableB for how far apart to plant, when toplant, days to first harvest, and yield.Do not bury stems deeper than theyare growing in the pot or cell. Begentle with plants so you do notdisturb roots. You can plant thetransplants by hand or use a tractor-pulled machine. Be sure to waterthem right away after planting.

Summer squash needs 50-60 days tofirst harvest. You can lengthen thegrowing season for summer squashby planting seeds every 2-3 weeks inspring. Pumpkins and winter squashneed all season to grow, 90-120 days.

8Planting and C

are

Table B. Planting guide

Planting time insouthern WIa,c

Plants orseedsneededfor 100 ftof row

Seeddepth(inches)

Spacing (inches)b

Days tofirst

harvestc

Estimatedyield(lb/ft ofrow)d

Vegetable Indoors OutdoorsBetweenrows

Betweenplants

Pumpkin May 1 May 10(seeds)

May 20(plants)

34-50plants

½ oz.seed

1 - 1½˝ 48-72 24-60 90-120 2

WinterSquash

48-96 36-96 90-120 2

SummerSquash

48-60 24-48 50-60c 1-2

Gourds 48-72 24-60 60-90 1⁄5 - 1⁄2

a Plant about 1 week later along the lower lake shore and in the central part of the state and about 2

weeks later in the north.

b If you use a plate-type seeder, the plate will make the spacing between plants.

c Plant summer squash every 2 weeks until the middle of the summer for a longer growing season.

d Estimated yields under less than ideal growing conditions; actual yields will vary widely withweather, soil fertility and cultural practices.

Soil preparationIt is important to control weeds beforeyou plant. You can use thesemethods:

Pull weeds by hand.�

Smother weeds with a cover�

crop (such as buckwheat).

Cover the soil with black plastic�

to heat it and keep out light.

Use weed killer sprays (herbicide�

sprays).

For more information on weed controlread the section on weedmanagement on page 13

Work beds 7-8 inches deep topromote good rooting. Never work wetsoil because this can cause soilcompaction. Compacted soils preventoxygen and water from reachingroots, and plants do not grow as wellor produce as much.

Raised bedsYou can use raised beds to improvesoil drainage and prevent compaction.

Raised beds are usually 4-5 feet wideand 100 feet long. Leave a 1-foot aisleon either side of each bed for a path.

Season extendersYou can make the growing seasonlonger by protecting plants from latespring frosts and early fall frosts usingthese methods:

Plant on a south facing slope.�

Plant on black plastic mulch.�

Cover young plants with a�

floating row cover.

Make a wind break. �

Plastic mulch. Plastic mulch raisesthe soil temperature early in theseason. You can add 1-3 weeks to thegrowing season with plastic mulch.Plastic mulch also keeps weedsdown. It helps prevent some plantdiseases because the fungus orbacteria spores from soil do not touchleaves. Many farmers in the Midwestuse black plastic mulch for pumpkins,squash, and gourds. Some farmersput drip irrigation tape down beforethey cover the soil with black plastic.

9Soil preparation

Lay down 1.25-1.5 mil black plasticmulch before you plant:

Dig a trench along each side of�

the row.

On a day with no wind, unroll the�

black plastic over the plantingbed.

As you go, push soil back in the�

trench to bury the edge of theplastic.

Place soil along all four edges of�

the plastic so it doesn’t blowaway. Wind can come in on anyside and lift the whole strip ofplastic.

The plastic should be tight so�

puddles do not form.

If you have puddles, poke tiny�

drain holes in the plastic.

You can also lay plastic mulch�

with a machine pulled behind atractor, called a plastic layer.

When you are ready to plant, cutholes where the plants go. Make theholes with a scissors or a propanetorch. If you cut holes with a scissors,remove the flap of plastic so it doesn’thurt the young plant.

Plants growing on black plastic needmore water. Some farmers use dripirrigation tape under the plastic.

Floating row covers. Floating rowcovers are special sheets of whitefabric made of spun-bondedpolypropylene which lets sunlight andwater through the fabric but stopsinsects:

You can use row covers to�

protect plants from frost, wind,and insects.

Row covers come in different�

weights and the thicker onescan warm plants by 4-8°F.

You can use them for a short�

time to cover pumpkins, squashand gourds in cold weather.

You can wash and re-use them�

for two to three seasons.

Put the row cover on top of the crop,gather the edges and loosely burythem along the crop row. As the cropgrows it will push up enough fabric toform a “floating” cover. You can alsouse rocks or heavy posts to holddown the edges. Take row covers offwhen the air is warm enough for thecrop to grow. Also take row covers offpumpkins, squash, and gourds whenthe plants are flowering because beesand other insects need to get to theflowers to pollinate them.

Windbreaks. If your field is in a windylocation you can put up windbreaks tohelp keep the field warm. The effectsof a windbreak cover an area 2 ½times the height of the windbreak. Forexample, a 10 foot tall windbreak willprotect an area up to 25 feet away.Many farmers plant a tall cover cropsuch as grain rye between rows ofpumpkins, squash, and gourds to actas a windbreak. To protect a wholefield you can also plant fast growingtrees or shrubs on one side, or use afabric or plastic mesh fence.

10Soil preparation

Soils and NutrientManagementGet a soil test before you plant a fieldfor the first time and then at leastonce every 3 years. For informationon how to collect samples and whereto send them for analysis, seeUniversity of Wisconsin Extensionpublication Sampling Soils for Testing(A2100).

Most soil tests include pH, organicmatter, phosphorus, and potassium.You can also ask to test for nitrate-nitrogen, calcium, magnesium, sulfur,boron, manganese, and zinc. You willreceive the results of your soil testalong with fertilizer recommendationsbased on how you will use your field.You can also test your potting soil thatyou use to grow transplants.

Soil pHSoil pH measures acidity and shouldbe at the correct level so the crop cantake up enough nutrients andminerals from the soil. Plants thatdon’t have enough nutrients andminerals plants can turn yellow.Pumpkins, squash, and gourds growwell in a wide pH range of 5.5-7.5.

Fertilizer needsPumpkins, squash, and gourds neednitrogen, phosphorus, and potassiumin large amounts and many othernutrients in small amounts. Table Cgives the amount of fertilizer theseplants need. Check your soil testresults to see how much of thesenutrients you need to add.

Nitrogen. Put down no more than halfthe amount of nitrogen you needduring the growing season when youmake the field ready for planting.

11Soils and Nutrient Management

Table C. Annual nitrogen, phosphate, and potashfor pumpkins, squash, and gourdsNitrogen Phosphate and potash

Organic matter Amount to applya Phosphate (P2O5) Potash (K2O)

% lb/a oz/100 sq ft lb/a oz/100 sq ft lb/a oz/100 sq ft

< 2 100 3.75 50 1.9 110 4.1

2.0-4.9 80 3.0

5-10 60 2.2

>10 40 1.5

aYield goal of 15-20 tons/acre. Follow guidelines from your soil test.

Work it into the soil. Later, when theplants have two or three true leaves,put down more. At that time, put it in astrip near the plant roots. If you needto give plants more nitrogen after that,do it when the vines begin to fill therows.

Plants that do not have enoughnitrogen are smaller and do notproduce as many pumpkins, squash,or gourds. Leaves will look lightergreen or a little yellow.

Potassium and phosphorous.Check your soil test results and TableC to see if you need to add potassiumand phosphorous. Spread it on thesoil when you make the field ready forplanting. Work it into the soil.

Choose fertilizer from organic orinorganic sources. Healthy soil hastiny organisms (microbes) that breakdown organic matter into nutrientsthat plants need to grow. Over time,organic fertilizer can build your soiland make the soil more healthy andfluffy which lets plants grow moreeasily. Inorganic fertilizers give plantsnutrients quickly but do not build thesoil. Some inorganic fertilizers have alot of salt which is bad for soilorganisms.

Organic fertilizers can come frommanure, compost, fish meal, bonemeal, and live compost tea thatincludes oxygen. Recent studies showthat live compost tea helps preventplant diseases and also givesnutrients to plants.

IrrigationPumpkins, squash and gourds needwater regularly because they use a lotof water and have big leaves. It is veryimportant that pumpkins, squash andgourds have enough water when theplants flower and grow fruit.

As plants grow, notice if leaves wilt inthe middle of the day. If so, they needwater. Plants that wilt for a short timewill not produce as big a yield. Plantsthat wilt often or for a long time mightdie. Pumpkins, squash and gourdsneed at least one inch of water everyweek.

Use either drip irrigation or sprinkler.Drip irrigation works very well under ablack plastic mulch system. Dripirrigation saves water. Mulch can helpkeep moisture in the soil. Pumpkin,squash, and gourd crops grow newroots at the place where a leaf andstem touch soil. Mulch that is too thickwill stop this root from growing.

12Irrigation

Weed ManagementYou must control weeds to grow agood crop of pumpkins, squash, andgourds. Weeds take water, nutrients,space, and light away from your crop.Also, weeds left in the field mighthave diseases or insects that canharm your crop. Be sure to watch yourfield for weeds and remove them assoon as you can.

Perennial weeds come up every year.Annual weeds start by seed and liveone year. Biannual weeds grow fromseed one year and flower the nextyear. Biannual weeds live only twoyears.

Before you plant, remove weeds. Youcan use these methods:

Pull weeds by hand.�

Smother weeds with a cover�

crop (such as buckwheat).

Cover the soil with black plastic�

to heat it and keep out light.

Use weed killer sprays (herbicide�

sprays).

During the growing season, removeweeds:

Cultivate or hoe regularly to�

remove annual weeds.

If you cultivate early in the�

season you can prevent mostweed problems.

If you use chemical weed killer sprays(herbicides), be sure you check thelabel:

Follow the rules on the label.�

Understand that the spray you�

choose is legal for the crops yousell.

Chemicals legal for a home�

garden might not be legal if yousell the crops.

Certified organic growers can�

only use approved organic weedkillers.

Mulch helps keep weeds down andalso helps prevent diseases andkeeps the soil moist. You can useblack plastic mulch to prevent weeds.Black plastic also helps warm the soilin the spring. Pumpkins, squash andgourds grow well on black plasticbecause they are warm weathercrops.

You can also use straw for a mulch. Athick layer of straw blocks sunlightfrom reaching the soil. Weed seedswon’t sprout.

13Weed Management

Harvest, Handling, and StorageSummer squash

Harvest summer squash 7-8 weeksafter planting. Harvest when the fruitare 2-3 inches across and up to 7inches long. Keep picking fruit every3-5 days so the plants produce more.Some customers look for “baby” orvery small young summer squash.Some farmers also sell squashflowers for people to eat. If you sellthe male flowers (after pollination) thefemale flowers can still grow fruit.

Be gentle when you handle summersquash. It bruises easily. Use a drytowel in the bottom of your harvestcontainer to make a soft cushion forsummer squash. Use a damp cloth towipe the squash clean. Do not putsummer squash in a water bathbecause summer squash is sensitiveto cold.

You can store summer squash for upto 1 week and keep good quality ifyou have the right conditions. Thestorage area should be cool andhumid:

Store summer squash at 40-45° F.�

Store summer squash at 95%�

humidity.

Winter squash and pumpkins

Harvest winter squash and pumpkins3-4 months after planting:

Winter squash and pumpkins are�

ready to harvest when the skinis hard.

They are ready when the skin is�

so hard you can’t poke a holewith your fingernail.

Pumpkins are ready when the�

orange color is deep and even.

Winter squash is ready when the�

skin turns dull and dry.

Gourds are ready when the stem�

is brown and dry.

Use a sharp knife or pruning�

shears to cut pumpkins andwinter squash from the vines.

Leave 3-4 inches of stem on the�

pumpkin. Customers look forpumpkins with stems.

Leave a 1 inch stem on winter�

squash, or no stem.

Leave a few inches of stem on�

gourds.

Do not carry pumpkins by the�

stem because the stem mightbreak.

Pumpkins with stems keep�

longer.

Wear gloves when you harvest�

because many varieties havesharp spines on their stems.

Be gentle and careful so fruit�

don’t get bruises or wounds.

Bruises and wounds spread rot.�

14Harvest, Handling, and S

torage

After harvesting “cure” pumpkins andwinter squash in a warm humid placeto make the rind hard, heal wounds,and make fruit last longer:

80-85°F and 75-85% relative�

humidity for 10 days.

Some farmers pick them and�

leave them in the field to cure.

Take them in from the field�

before hard frost, (when nighttemperatures are colder than28°F).

Do not cure acorn squash.�

After curing, use these techniques tostore winter squash and pumpkins:

Keep them in a shed or barn.�

Store them between 40 and 55°F�

and 50-70%.

Keep them dry.�

Store them off the floor, for�

example on a wooden pallet.

Give them a lot of air flow; use a�

fan.

Do not stack, or no more than 3�

high.

Do not let them touch each�

other.

Remove rotten ones.�

Do not store pumpkins near�

apples.

Use old carpet in the packing�

area as a cushion to preventbruises or wounds.

Acorn squash will keep up to 2months. Pumpkins, winter squash,and gourds will keep for 2-3 months.

You can pack them in waxedcardboard boxes. Wipe them cleanwith a cloth before you bring them tomarket.

15Harvest, Handling, and Storage

Preventing Stress on Your BodyTry to prevent stress on your bodywhen you grow pumpkins, squashand gourds:

Try to prevent stooping or�

bending.

Change your position often. �

Sit on a stool or a pail. You can�

use a stool that you wear as abelt, or a stool on wheels thatrolls along the row like a cart.

Use garden carts and wagons as�

often as you can so you do notlift and carry so much.

If you use a standard plastic�

container that stacks and iseasy to load, unload, and clean,you will save time.

In the place where you pack yourcrops, use these techniques to makepacking easier:

Set up your wash and pack area�

so you walk, carry, stoop, andbend as little as possible.

Set up work areas the same�

height as a table.

Short people might want to stand�

on a stool to reach the tablesmore comfortably.

Make a smooth level floor so it is�

easier to work with carts andwagons.

To move boxes of produce, there�

are systems you can use withsmall pallets and hand pallettrucks.

You can also buy roller table to�

move heavy boxes of produce.

There are examples of tools thatmake work easier from the Universityof Wisconsin-Madison Department ofBiological Systems Engineering. Go

to the department website(http://bse.wisc.edu/) and look under‘Department Links’for the HealthyFarmers, HealthyProfits Project. Clickon Tip Sheets andgo to the category

forvegetablegrowers.

16Preventing S

tress on Your Body

Pest and DiseaseManagementDiseasesThe common diseases that attackpumpkins, squash, and gourds aredowny mildew, powdery mildew, blackrot, and bacterial wilt. All of thesediseases except bacterial wilt arecaused by different fungi. Bacterialwilt is spread by a beetle. Use thesepractices to prevent fungus diseasesin pumpkins, squash and gourds:

Plant resistant varieties.�

Plant disease-free seed.�

Do not plant in poorly drained�

soil.

Wait 2-4 years before you plant�

pumpkins, squash, or gourds inthe same field.

Keep the field clean of weeds.�

Destroy old plants, stems and�

leaves.

Remove old pumpkins, squash,�

or gourds from the fields.

Use drip irrigation instead of�

sprinkler.

Give plants enough fertilizer and�

water.

Harvest when the fruit are�

mature.

Prevent cuts and wounds on the�

fruit.

Keep pumpkins, squash and�

gourds dry after harvest.

Store crops at the right�

temperature and humidity.

Wash and dry equipment after�

you use it.

17Pest and Disease Management


Downy mildewDescription: a fungus(Pseudoperonospora cubensis)invades and kills the leaves. Early inthe life cycle you see yellow areas onthe leaves. With more time, infectionmakes the leaves turn tan or brown. Ifthe weather is damp, a fuzzy white orgray growth covers the underside ofthe leaves. Later these areas turnblack. Leaves die. The plant formsfewer fruit and poor quality fruit. Thewhole plant can die. Downy mildew isworse in cool weather. Pumpkins,squash, and gourds with downymildew get other diseases moreeasily.

Disease cycle: Over winter, thefungus lives in parts of diseasedplants left in the field. Spores blow inthe wind on to leaves of other plants.

Wet weather with dew, fog, or raincauses more infection.

Management: use the preventiontechniques above and also:

Give good air flow between�

plants; don’t plant too closetogether.

Wait 3 years before you plant�


When the weather is damp and�

cool, try a spray of compost tea.

Powdery mildewDescription: Many different fungicause powdery mildew. You see lightyellow spots on the oldest leaves.Later a white powdery growth formson leaves and stems. The powder canbe on the top of the leaf and thebottom side of the leaf. Leaves can

18Pest and D

isease Managem

ent

Downy mildew


Powdery mildew

Don Ferrin, Louisiana State University AgriculturalCenter, Bugwood.org

shrivel and die. Sometimes the wholevine dies. Powdery mildew affectsolder plants first. Pumpkins, squash,and gourds with powdery mildew getother diseases more easily. Theyproduce fewer fruit, smaller fruit, andpoor quality fruit.

Disease cycle: Over winter, thefungus lives in parts of diseasedplants left in the field. Spores blow inthe wind on to leaves of other plants.Spores start growing if there ismoisture. Weather with hot days andcool nights causes more infection.

Management: use the preventiontechniques above and also:

Give good air flow between�

plants; don’t plant too closetogether.

When the days are hot and�

nights are cool, try a spray ofcompost tea or baking soda.

Black rotDescription: a fungus (Didymellabryoniae) causes brown or blackareas on the fruit. At first, spots on thefruit or leaves look water-soaked.Later, a gooey mass oozes spores.White and black growth forms on thefruit and it begins to rot. Rot can startin the field or in storage.

Disease cycle: Over winter, thefungus lives in parts of diseasedplants left in the field. Fungus sporesalso live on seeds. Spores blow inwind on to leaves of other plants.Spores infect the plant and startgrowing if there is water on the leaves

for at least one hour. If the leaves staywet, the infection grows. Infection alsostarts where cuts or wounds on fruitmake an opening.

Management: use the preventiontechniques above.


Black rot

Elizabeth Bush, Virginia Polytechnic Institute and StateUniversity, Bugwood.org

Bacterial wiltDescription: a bacteria (Erwiniatracheiphila) causes leaves to wiltduring the day. At night or on cloudydays the plants recover. Plantsinfected with bacterial wilt can havethe same symptoms as plants thatare being attacked by the squash vineborer, or plants that are infected withFusarium fungus. If you cut a stem,hold the two pieces together for 10seconds, and slowly pull them apart.If the pumpkin, squash, or gourd hasbacterial leaf spot, you will see asticky white sap.

Disease cycle: The bacteriaoverwinters in the cucumber beetle.When the beetle feeds, the bacteriainfects the plant. Food and watercannot travel through the plant and aweek later the plant wilts.

Management: The only way tomanage bacteria wilt is to preventcucumber beetles from feeding. Thereis no treatment for plants after theyare infected. Cucumber beetles areyellow-green and 1/5 inch long. The

striped cucumber beetle has threeblack stripes down its back. Thespotted cucumber beetle has twelveblack spots on its back. The undersideof a cucumber beetle is black.

You can use row covers early in theseason to control the cucumberbeetle and prevent it from feeding. Besure to lift the row covers in time forbees to come when flowers open.

Some farmers trap the beetles withyellow sticky cup traps. Sprays ofkaolin clay (sold as “Surround”) canalso prevent beetles from feeding.Other farmers have tried to plant arow of “trap crops” around the field toattract and keep the beetles. You cankill them there before they move tothe market crop. If you are an organicgrower, check that the method youuse to kill the beetles in the trap cropis okay for organic crops. Somefarmers use a propane flame burnerto kill the beetles in the trap crop.Dark green zucchini or blue hubbardsquash are good varieties to use astrap crops for cucumber beetles.

20Pest and D

isease Managem

ent

Bacterial wilt

Howard F. Schwartz, Colorado State University, Bugwood.org

VirusesPumpkins, squash and gourds canbecome infected with viruses. Plantswill be weak, produce less fruit, andfruit will be poor quality. Preventviruses from infecting crops, becausethere is no treatment for plants afterthey are infected. If you think a planthas a virus, remove it from the fieldquickly and destroy it. Plant resistantvarieties and control weeds. If youknow that an insect common to yourarea carries a virus, prevent theinsect from feeding on your pumpkins,squash or gourds. Use the techniquesdescribed above in the section aboutbacterial wilt and cucumber beetles.


Insect ManagementSquash vine borerDescription: Squash vine borers area serious pest of pumpkins, squash,and gourds. They are worms or grubswhich are the larva of a moth. Adultslook like a wasp and are 1 ½ -2inches long. They have greenish-brown front wings and clear backwings. Squash vine borers live aspupa in the soil. In late June or July,adult moths emerge. They fly duringthe day. They are strong fliers andsometimes you can hear a buzzingsound when they fly. It is important to

notice these insects because you canlearn to look for the eggs and larvaafter you see the moth.

Female moths lay small, flat, browneggs at the base of pumpkins,squash, and gourds. They lay eggssingly, not in a group. About a week orten days later the eggs hatch. Younglarva bore into the plant and feed fortwo-six weeks.

Larva are white with a brown head,and they grow to be almost one inchlong. When they are fully grown theyleave the plant and enter the soil toform a pupa. As the larva feed, theyeat through the middle of the stems.Water cannot flow through the stemand the plant wilts. At first the plantswilt only in the middle of the day. Laterthe plant wilts completely and can die.Look for holes near the base of wiltingstems. Also look for a powder thatlooks like sawdust. This is calledfrass. If you see frass, split the stemthe long way to look for the larvafeeding inside.

Management: It is very difficult tocontrol squash vine borers. The bestway is to prevent them. Look for theadult moths and then check yourplants regularly to look for eggs andlarva. Some farmers use traps to seethe moth. Make traps from yellowbowls filled with water. The moths willbe attracted to the yellow containerand fall into the water. Put the trapsout by late June and check themevery day.

22Insect M

anagementSquash vine borer


If you notice adult moths of thesquash vine borer, you can use rowcovers to prevent moths from layingeggs on the plants. Some farmersregularly put row covers on plants inlate June or early July. The row covershave to be tight to the ground somoths can’t get to the base of theplants. Keep the row covers on forabout two weeks after you see theadult moths. If plants are flowering, besure to lift the row covers in time forbees to come when flowers open.

Some farmers plant a second crop ofsummer squash in early July. This latecrop will grow after squash vine boreradults have finished laying eggs.

If you see plants that have been killedby squash vine borers, remove theplants from the field quickly anddestroy them.

Squash bug Description: Squash bugs are aninsect that is dark gray and about 5/8inches long. They suck sap from theleaves and stems. The plants wilt andthen turn black and die. Squash bugsalso eat the fruit on squash andpumpkins. Squash bugs live inprotected places. Over winter they livein buildings and in parts of plants leftin the field. In spring and summerthey lay eggs on the underside ofleaves. Eggs hatch into light green orgray immature bugs called nymphs.You can see many nymphs togetheron leaves and fruit.

Management: It is difficult to control

squash bugs. The best way is toprevent them. Some varieties ofpumpkins, squash, and gourds aremore likely to be eaten by squashbugs than others. During the growingseason you can follow these steps tocontrol squash bugs:

23Insect Management

Squash bug


Put boards on the ground near�

the squash plants at night. Thenext morning you can kill thesquash bugs that you find underthe boards.

Look for the egg masses�

underneath leaves and destroythem.

You can spray an insecticide to�

kill the nymphs. Certifiedorganic growers can only useapproved organic insecticides.

Pyrethrum and Neem are some�

insecticide sprays to kill squashbug nymphs. Check with yourorganic certifier about theregulations for these sprays.

If squash bugs are a problem oneyear, follow these steps to preventthem next year:

At the end of the year, do not�

leave the old plants in the fieldbecause squash bugs willoverwinter under them.

You can remove the old plants or�

till them under the soil.

Plant a cover crop in the field�

where the squash bugs were.

The next year, do not plant�


Do not use thick mulch around�

the crop, because squash bugscan hide in the mulch.

Cultivate the soil so no plant�

debris is left as a place forsquash bugs to hide.

Striped and spottedcucumber beetlesRead about these insects above inthe section about bacterial wilt.

24Insect M

anagement

Striped and spottedcucumber beetles


This publication was developed by the University of Wisconsin-ExtensionEnvironmental Resources Center in collaboration with the WisconsinDepartment of Agriculture, Trade & Consumer Protection and supported by agrant from the USDA Risk Management Agency.

Text by Astrid Newenhouse, Associate Scientist, University of Wisconsin-Extension Environmental Resources Center. Special thanks to Karen Delahaut.

Layout and design by Laurie Lawrence, Agency Art Director, WisconsinDepartment of Agriculture, Trade & Consumer Protection.

The publication can also be viewed and printed from pdf format on the web athttp://learningstore.uwex.edu/

Copyright 2011 by the Board of Regents of the University of Wisconsin System.University of Wisconsin-Extension is an EEO/Affirmative Action employer andprovides equal opportunities in employment and programming, including Title IX and ADA requirements. ISBN: 978-0-9821972-5-7

UWEX Publication A3904-03 (02/12)

WI DATCP pub#: mk_fc_81.qxp (02/12)

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