Removed from on-line listing due to outdated control information.

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Insects attack vine crops from the time of seeding until harvest.  They can reduce the stand, defoliate the leaves, feed on roots or flowers, transmit bacterial and viral diseases, and create wounds that help fungal pathogens enter the plant. There are 7 major insect pests to consider: seedcorn maggot, cucumber beetles, squash vine borer, green peach aphids, melon aphids, mites, and whiteflies.  Growers need to protect the crop against insect damage while concurrently ensure pollination by bees.  Row covers are effective against beetles, vine borers, and squash bugs, but they must be removed during flowering to allow for pollination.
 

Seed Corn Maggots

Seed corn maggots injury is related to root growth and soil temperature.  When the soil is cool, feeding injury is more severe.  When the soil is warm, root growth outpaces maggot feeding.  Do not plant vine crops in cool soils.  The adult flies are attracted to organic matter, so manure applications or plowing up cover crops should be done early - at least 1 month before planting.  Completely covering transplant root balls may help.  Adding a seed treatment in the hopper box is a good practice for direct-seeded crops.

Striped Cucumber Beetle

The striped cucumber beetle is our most serious insect pest.  Overwintering adults invade in large numbers, transmit a bacteria that causes bacterial wilt, defoliate, lay eggs that result in larval feeding on roots, and go through 2 generations.  Our ELISA data estimates that that at least 5-10% of the overwintering adults carry the bacterial pathogen, and most of the transmission occurs from defecation into wounds. The carrying rate can go up to 70%.  The amount of bacterial cells put into a plant determines how fast and severe the disease symptoms will be.  Disease progress is made worse when beetles congregate on plants, because then more feces, and thus more bacterial cells, get moved into wounds.

Admire can be applied directly to transplants or added with drip irrigation. High rates can cause phytotoxicity, but low rates applied to transplants gave about 10-14 days control of field-collected insects bioassayed in the lab. The figure shows the percent mortality at two rates applied directly to transplants, 1 day prior to transplanting. Uptake is primarily through the roots. We have seen dramatic yield increases of muskmelon with just the small transplant application when this controlled the immigrating adults and a second generation did not develop.  However, transplant application alone was not sufficient to control cucumber beetle populations.  A combination of a transplant application followed by a single chemigation through the drip irrigation can give longer control, and result in increased yield on black or yellow mulch (see Fig.). Provado is not labeled on cucurbits. Other effective materials are listed in the Commercial Vegetable Production Guide.

Lou Otjen helped develop rate information to control cucumber beetles invasion at transplanting, with Admire.  We recommend a very low rate (0.02 ml/plant) to treat transplants about 1 day prior to planting in the field.  To treat a flat of 200 transplants with Admire at this rate, a grower would need to dilute 4 ml (0.135 oz) of Admire in a volume of water sufficient to soak to soil mix evenly. This treatment will protect the plants for about 2 weeks, and after that may be followed by field application.  To help make other conversions: multiply 0.02 ml per plant times the number of plants in your flat.  For example, use 20 ml to treat 1000 transplants. (This rate is just a little higher than suggested for tomato transplants, which is - 15 ml - or 0.5 ounce - per 1000 transplants). You can convert ml to oz by dividing by 29.6 (there is 29.6 ml in a fluid oz).  Be careful of phytotoxicity (burning the plants) at higher rates.  We observed burning of leaf margins at 0.04 ml/melon plant at the 2-leaf stage, although these plants did grow out of this in about 2 weeks.

The best way to apply Admire to the field is through an injector connected to a drip irrigation system.  As with all chemical injections, the irrigation system should be primed with water prior to beginning the injection, and the material should be injected slowly to provide even distribution.  Remember: the more evenly distributed the material is, the better job of protection, and the chance of phytotoxicity will be reduced (i.e. the more emitters on your drip tubing the better).  It is also important that the zone of moisture created by the drip tubing be within the root zone of the crop because it is the roots that will move the material into the plant.  ALWAYS FOLLOW THE LABEL.  Below is a table which estimates the number of ounces (oz) or milliliters (ml) of Admire needed per 100 row-feet for application rates of 16-24 oz/A.  The amount required to treat 100 ft row is very small and not easily achieved by commonly available measuring devices.  We recommend that growers with small fields use milliliters as a measurement unit, and use syringes if available (without a needle-they will plug up) for extracting these amounts.  A syringe without the needle will provide a very accurate and safe method of measuring these small quantities.

These rates were calculated for irrigation systems supplying a 3 foot bed.  The amount of material applied should be the same regardless of whether a single or double row occupies a bed of this size.

If a drip irrigation system is not available to deliver the pesticide to the root zone, it can be applied by directing a spray or drench into the soil at the base of the plant.  It is important that the material be applied when the soil is moist, or with enough water to soak the soil to the depth of the root zone.  If it is applied only to the surface of the soil, the roots will not have good access to it. We would recommend applying the material directly to the base of the plant when the soil is moist and with at least 10 ml of water per plant for young plants (<4 true leaves) and 50 ml of water for larger plants.  This can be achieved with a backpack sprayer rather efficiently, but you need to calculate how much time it takes for your backpack sprayer to deliver a 10 ml volume of water. To calculate the total volume of water to put in your backpack sprayer, multiply the number of plants you want to treat by the volume of water per plant.  For example, let’s say you wanted to treat a 100 foot row of cantaloupe with 16 oz/A of Admire.  If your plant spacing was 2’ then there would be 50 plants in that row.  If the plants were young you would only need 10 ml of water per plant (minimum – please feel free to increase this amount if you wish).  Multiply 50 plants by 10 ml and you will discover you need 500 ml of water to treat this row.  Add 500 ml of water to the backpack sprayer and then add 3.26 ml of Admire, mix well, and apply.  The trick with this type of delivery system is to estimate how long it takes to deliver 10 ml (a very small quantity) from your backpack sprayer.  Often this is just a quick shot from the trigger.  Remember to keep the nozzle close to the soil and direct the spray toward the base of the stem.  Please test the output of your sprayer with water prior to performing these calculations, and remember - do not apply Admire within 21 days of harvest.

Biological and cultural controls also effect the striped cucumber beetle. Entomopathogenic nematodes can help as a biological control of the larvae feeding on the roots.  One species (Steinernema riobravis) introduced through the drip irrigation reduced larval populations by about 50%. The figure compares emergence in untreated plots and plots treated with Steinernema riobravis. Black plastic mulch alone reduces the survival rate of the larvae by as much as 50%.  Yellow mulch, however, attracts the adults. Also, a tachinid (fly) parasitoid of the adults occurs naturally in Pennsylvania, and was measured at fairly high levels in New York.

Aphids

Aphids are often controlled adequately by natural enemies until late in the season, unless you are in an area that has had problem with virus.  If virus has not been a concern in your area, then it helps to limit insecticides to encourage natural enemies. However, if virus has been a problem, deterring aphids from moving into fields with reflective mulches, using resistant varieties when available and preventing movement of aphids from weeds or among different plantings becomes very important.  Resistant varieties using both conventional and transgenic methods are available for squash.  Successive plantings make it harder to control virus transmission, as the vectors that build in one crop move onto the next.  Also, both the green peach and the melon aphid have shown problems with insecticide resistance.  Careful follow-up scouting after a spray is important, and be prepared to try other classes of insecticides.  There are new materials that are selective against aphids.

Squash vine borer has one generation a year.  Problems are typically more severe in squash, pumpkins and gourds than melons or cucumber.  Scouts can look for the brightly colored moths flying during the day, frass at entry holes, or use pheromone traps to determine when they are flying.  However, pheromone traps used in small planting may make problems worse by attracting moths that lay eggs singly among the fewer plants.  Small plantings result in eggs being concentrated onto fewer vines.  Timing insecticides to when the eggs are hatching and the larvae are very young is the key to control.

Squash Bugs

Squash bugs are more likely to be a problem in squash and pumpkins.  Scouting is best directed at the coppery-brown eggs, and control directed against nymphs.  Getting thorough coverage underneath leaves is essential.  The insects are well protected under the large leaves of vine crops.  Make sure you are not moving into canopy closure with a population of squash bugs.  Scouting at early flowering helps.

Mites

Mites require large populations to cause serious damage, but their populations build up very quickly when temperatures are hot (>80F).  Dry weather (<50% RH) also is correlated to mite build-up.  They can complete development in only 5-7 days under these conditions, which is 2 to 3 times faster than many of our other vegetable pests.  Often mites move in from nearby crops or weeds, and initial densities are high near field edges.  Several miticides have been added to the Veg. Guide in the past 1-3 years.

Whiteflies

Whiteflies are an occasional pest in Pennsylvania, but where they occur, they can also build up to very high densities.  The species we have do not overwinter well in Pennsylvania, and typically move in from greenhouse material, or from other crops.

Pollination

Pollination. Vine crops have 2 types of flowers: cucumbers, squash, pumpkin and watermelon have separate male and female flowers, while muskmelon have male and hermaphroditic (bisexual) flowers. Growers must support pollination by bees.  The dense and sticky pollen needs to be transferred to the female flowers to ensure fruit that is well shaped, and to optimize yield.  Fruit size and shape is related to the numbers of seeds produced, and each seed requires 1 or more pollen grains.  Flowers are usually open and attractive to bees for only 1 day, and pollination must take place on the day that the flower is open.  Ensuring the presence of 1 to 2 honeybee colonies per acre, and up to 3 hives per acre, has a reliable method of pollination in the mid-Atlantic.  Colonies should be strong: at least 1,200 square inches of brood per colony and enough adults to care for them.  Vine crops are not especially attractive to honeybees.  Moving colonies into fields after blooming has started helps ensure that the bees work the vine crops.  When bees are in the field, insecticides should only be applied near the evening, when the bees have returned to the colony.  Notifying beekeepers and written contracts are good practices.  Finally, we need to start encouraging our native ground-nesting bees.  Several species exist which may be very useful cucurbit pollinators.

Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.

*** Disclaimer ***

Authored by: Shelby Fleischer, Associate Professor

Last updated January 2001

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