By Lorena Lopez, Alejandro Del Pozo, and Tom Kuhar.
We continue to see severe pickleworm infestations in squash and pumpkins grown in the Hampton Roads area (Table 1). Summer squash season is gone but beware of your pumpkins. Systemic insecticides are recommended to mitigate pickleworm infestations since contact insecticide cannot reach the larvae that burrow into fruits and flower buds (see the link below for insecticide recommendations). Pickleworm larvae can burrow into pumpkins after harvest as well when they are beautifully displayed in your porches or gardens.
Crop
Row
Fruits_with_holes
Undamaged_fruit
Percent_damaged
Zucchini
2
5
5
50
Zucchini
4
4
6
40
Pumpkin
1
11
4
73
Pumpkin
2
12
3
80
Table 1. Percentage of zucchini infested with pickleworms in the Hampton Roads AREC on Sep. 27, 2022
By Lorena Lopez, Alejandro Del Pozo, Helene Doughty, and Tom Kuhar
After pickleworms and melonworms showed up late in the summer season, we detected severe infestations (Table 1) in the Hampton Roads area and found both pests in the Eastern Shore AREC (Painter, VA) infesting summer squash and pumpkins. Beware of your pumpkins and examine your plants weekly for these pests which can be severely damaging and affect significantly your yield. In the links below you can find details on how to ID these pests and recommendations on what insecticides to use in case of infestation.
Crop
Row
Fruits_with_holes
Undamaged_fruit
Percent_damaged
Zucchini
1
6
4
60
Zucchini
2
5
5
50
Zucchini
3
5
5
50
Zucchini
4
9
1
90
Pumpkin
1
11
4
73
Table 1. Percentage of zucchini infested with pickleworms in the Hampton Roads AREC on Sep. 19, 2022
This week, pickleworm larvae have been detected in the Virginia Beach area, Chesapeake, and Portsmouth. If you have late plantings of squash beware of the presence of this pest in the area. Also, pumpkins could be infested by pickleworms borrowing into the fruit or feeding on the surface of the fruit. Here is a brief description of pickleworm larvae and adults, as well as options for management.
Pickleworms feed on wild and cultivated cucurbit species. Adults are not active during the day, only at night when females lay their eggs close to flowers or flower buds. The larvae burrow into the fruit where it feeds and develops. Larva color varies from light green to translucent with multiple dark spots and varies in size from 0.05 to 0.6 inches long.
Management: Pyrethroid insecticides can be effective at controlling this pest if sprayed in a timely manner (i.e., lambda-cyhalothrin, permethrin, bifenthrin, Baythroid XL, Mustang Max, etc.), but they are not IPM compatible and can result in outbreaks of secondary pests such as aphids. Usually two or more sprays of pyrethroids in late summer can cause severe aphid problems. Other insecticides that control pickleworms include Radiant and Entrust (spinosyns), the diamide insecticides like Coragen and Harvanta, the insect growth regulator Intrepid, and the lepidopteran-targeting insecticide Avaunt eVo (Indoxacarb). These products will have less non-target impacts than pyrethroids and also control pickleworm.
Pickleworm larva inside a zucchini in Virginia Beach.Adult pickleworm moth.
Last year, we at Virginia Tech started a pickleworm and melonworm monitoring program consisting of information exchange between cucurbit growers and extension agents across the state that looked for these pests’ damage to cucurbit blossoms or fruits. In 2021, we recorded up to 80% of squash fruits or flower buds infested with either pickleworms or melonworms. This year we continued with the monitoring efforts by monitoring closely summer squash fields in the Eastern Shore, Blacksburg, and Chesapeake area and no pickleworms nor melonworms have been detected.
Additionally, we set up traps with pickleworm pheromone lures in squash and pumpkin fields in Montross, Hillsville, Cape Charles, Painter, Hampton Roads, and Madison County. If these moths are present in the area, they will be attracted to the lure at night when they are active. After two weeks of trapping, no pickleworms or melonworms have been caught in the traps. We will continue to trap these pests as the summer squash season finishes and the pumpkin season continues and will keep you updated.
By Lorena Lopez and Helene Doughty; Eastern Shore AREC, Entomology Lab
We continue to see a decrease in the incidence of pickleworms infesting squash at the Eastern Shore Agricultural Research and Education Center (AREC). This week in our last zucchini trial of the year, pickleworm larvae were found only on 10% of the sampled flowers (4 out of 40 flowers). This is an important improvement considering that seven weeks ago we were finding pickleworms in approximately 80% of our samples. This tendency will continue as we get close to winter and low temperatures.
By Lorena Lopez and Tom Kuhar; Virginia Tech Department of Entomology
Last week, we continued to find pickleworms borrowing into zucchini squash flowers (Fig. 1) in the Eastern Shore, whereas the incidence of melonworms borrowing in the fruit started to decrease. Additionally, there was evidence of pickleworms borrowing into garden-grown pumpkins in the Chesapeake area, including new borrowing holes found on fruit harvested after a few days (Fig. 2-3).
In the Northern Neck (Montross and Warsaw specifically), zucchini squash, crookneck squash, and pumpkin fields were checked for pickleworm and melonworm infestation in mid-September and early October. There was no evidence of worm infestation.
Figure 1. Pickleworm larva (Diaphania nitidalis) in a zuchinni squash flower (Photo by K. Grabowski) Figure 2. Pickleworm larva emerging from a pumpkin after long exposure to the sun. Leaving the fruit outdoors may cause the fruit to heat up enough to cause disturbance to the pickleworm (Photo by K. Grabowski) Figure 3. Pickleworm injury to garden-grown pumpkin in the Cheasepeak area (Photo by K. Grabowski)
Increased infestations with pickleworm and melonworms continue to be observed this week in the Eastern Shore of Virginia. Yesterday, Sep. 2nd 2021, these pests were found feeding on yellow summer squash, green zucchini, and dumpling winter squash crops. All plants sampled in Cape Charles (n= 30) and Machipongo (n= 20) showed at least one fruit and one flower bud with either pickleworms or melonworms, many times with both. If you have any squash crops at the moment, please continue to monitor your plants.
Both melonworms and pickleworms have been detected in squash plantings yesterday in Cape Charles and Machipongo farms. Approximately, 80% of the plants showed at least one flower bud/fruit with borrowing injuries. Most of the squash fruit and flower buds contained 1-2 melonworms in the latest stages of their larval development (4th-5th instar, Fig. 1). Pickleworms on the other hand, have just started to show up in the area and only 1st to 3rd larval instars were found, most of them on top of flower buds and growing fruit (Fig. 2). Both pests were also detected in one cucumber planting on approximately 30% of the plants sampled. These pests have been detected in squash plantings in Blacksburg this week at a lower infestation rate compared to the Eastern Shore.
Well-timed insecticide applications are crucial for the management of these pests and recently hatched caterpillars that haven’t borrowed into the plant tissue are more susceptible to insecticides. However, once they borrow inside fruits and flower buds, contact insecticides are usually not enough to suppress these pests. The use of systemic insecticides is preferred.
Useful tip: Pickleworms and melonworms are NOT the same as squash vine borers. Squash vine borers borrow into the stems causing severe damage and eventually plant death (Fig. 3), unlike pickleworms and melonworms that feed mostly on the reproductive parts of the plant and occasionally the leaves.
Fig. 1. Melonworm larvae inside squash fruit.
Fig. 2. Pickleworm larva on top of flower bud.
Fig. 3. Squash vine borer inside the stem.
If you find borrowing damage in cucurbit crops on your respective farm or gardens, please contact me at lorelopezq257@vt.edu
Stay tuned for the next update!
Lorena Lopez, Ph.D., Department of Entomology, Eastern Shore AREC, Painter, VA Photos by Lorena Lopez.
We at Virginia Tech are starting a pickleworm and melonworm monitoring program. This program involves information exchange between cucurbit growers and extension agents across the state that look for these pests’ damage to blossoms or fruit and report it back to me, Lorena Lopez, a vegetable entomologist at the Eastern Shore AREC. I will send out a weekly alert of the incidence of these pests in the state, based on this information chain and monitoring efforts in cucurbit crops located in Blackburg and the Eastern Shore AREC. The goal is to keep growers updated and help them manage these sporadic late-season pests.
A quick overview of these pests:
Both pickleworms and melonworms feed on wild and cultivated cucurbit species. Pickleworm adults are not active during the day, only at night when females lay their eggs close to flowers or flower buds. The larvae burrow into the fruit where it feeds and develops. Larva color varies from light green to translucent with multiple dark spots and varies in size from 0.05 to 0.6 inches long. Melonworm adults are usually found during the day on the plants but they can be active during day and night. Females lay their eggs on the underside of the leaves. Larva feeds mostly on leaves and can cause damage by skeletonizing them. However, melonworm larvae can also feed on the fruit and on some occasions can borrow into the fruit like pickleworms. Melonworm larvae are usually light green with two white lines in the back and have a similar size to the pickleworm larvae. Adults of both pests are very hard to differentiate.
Pickleworm larva (J. L. Capinera, UF/IFAS)
Melonworm larva (L. Buss, UF/IFAS)
Fruit damage caused by pickleworm and melonworm larvae (L. Lopez, Virginia Tech)
Early this week we found melonworms in our yellow summer squash at the Eastern Shore AREC. Yellow summer squash is one of the preferred hosts of these pests. All melonworm larvae were found feeding inside the fruit which is uncommon for this pest. We haven’t found any pickleworms yet.
The help and communication network between extension agents, cucurbit growers, and entomologists like myself is vital for the monitoring program. Thus, if you find borrowing damage in the cucurbit flowers or fruit in your respective farm or gardens, please contact me at lorelopezq257@vt.edu
Stay tuned for next week’s update!
Lorena Lopez, Ph.D., Department of Entomology, Eastern Shore AREC, Painter, VA
In the past weeks, a few strawberry growers have expressed their concern about the possibility of cyclamen mite infestations. After visiting some strawberry farms in the Chesapeake area this week, I found symptoms of cyclamen mite damage in a few fields. Because of the small size of the mites, I took leaf samples from the symptomatic plants and confirmed the presence of the mites in the laboratory.
The cyclamen mite is a serious pest of strawberries. It has
been reported in most strawberry-producing states. Cyclamen mites are tiny
mites (0.001 in long) that feed on the tissue of nonexpanded and newly unfolded
leaves in the strawberry plants. Adults and immatures of the cyclamen mite are
considerably smaller than two-spotted spider mites and cannot be easily seen
with the naked or a hand lens. Symptoms of cyclamen mite infestation include
severely crumpled and crinkled leaves, as well as stunted plants.
The presence of cyclamen mites was confirmed mostly on ‘Ruby June’ strawberries, but they can infest any strawberry cultivar. Strawberry growers in the Virginia Beach metropolitan area and the eastern shore should beware of the presence of this pest mite in their field. There are very few miticides available for the control of cyclamen mites. Unfortunately, the same products used for the control of two-spotted spider mites do not always provide control for cyclamen mites. The best performing product against this pest is Portal (fenpyroximate). Agri-mek (abamectin), is also labeled for cyclamen mites. Despite being miticides, Acramite and Magister are not labeled for control of cyclamen mite and may not provide enough protection against it.
Dr. Lorena Lopez Department of Entomology Virginia Tech | Eastern Shore Agricultural Research and Extension Center (ESAREC) (954) 529 9042 | lorelopezq257@vt.edu
