Q&A: Why do my cucumber and zucchini plants wilt?

One Spotted and multiple Striped Cucumber Beetles, feeding on overripe pumpkin. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

Q: Last summer I had cucumbers and zucchini wilting and dying even though I’m pretty certain I didn’t have root rot or squash vine borer. What should I try this year so I can hopefully get a harvest?

A: Bacterial wilt disease, transmitted by cucumber beetles is the prime suspect for crop failure in this instance. Both of these garden pests – Striped Cucumber Beetle and Spotted Cucumber Beetle – are native to North America and can cause serious damage to vegetables in the squash/cucumber family, though they can also feed on unrelated fruits, vegetables, and ornamental plants.

Although their feeding causes direct plant damage, the main issue comes from their introduction of one or more plant pathogens. These beetles can transmit diseases like bacterial wilt and viruses, none of which are curable.

Delaying the planting of squash and cucumber transplants until mid-June may evade the host-seeking adults. Until they bloom, cover plants with insect netting or row cover (the former is ideal as it doesn’t trap heat). Bees will need to reach the flowers for pollination, but once the fruits start to develop, plants tend to be less susceptible to infection. Since more than one beetle generation can occur per year, clean-up veggie garden debris in autumn to deny remaining adults overwintering shelter.

For now, ‘County Fair’ is the only available variety resistant to bacterial wilt. This pickling cucumber is parthenocarpic– it produces mostly female flowers that don’t require pollination to set fruit. The Cucumber Beetles page at the Home & Garden Information Center has more information about these insects and their management.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun. Read more by Miri.

Send home gardening questions to Ask Extension at the Home & Garden Information Center

The more the merrier: community actions for pollinators

bumble bee on a purple coneflower

Besides it being the month when summer starts, June is a great month because it is when Pollinator Week happens! 😊

Tagging along with that week, in today’s post I want to talk about some actions you can take with(in) your community to help pollinators! Because, if we want to help pollinators, a very valid and effective way to amplify your actions is to get others on board! Here, a non-extensive list of ideas.

1. Become a Bee City

Ask your City or Campus to become a certified Bee City or Bee Campus USA. Bee Cities and Campuses are certifications that cities and campuses across the USA can obtain if they implement a series of actions (“commitments”) established by the Xerces Society. Once these actions are done, the City or Campus in question becomes certified as a pollinator-friendly space. The types of actions outlined are really activities that lead to increasing education on pollinators and pollination, to improving pollinator habitat on the institution’s land, to promoting actions in the way that the institution functions that may allow for increasing pollinator support (see here for city commitments and here for campus commitments). Becoming a Bee City or Campus is not hard, and most institutions say yes if their members ask. If you think this is something you would like your City and/or Campus to do, reach out to your representatives or leadership and get them on board! And to have an idea of what cities and campuses are already involved, take a look at the Bee City USA affiliates.

2. Organize a Pollinator Week Event

Pollinator Week is a National event organized by the Pollinator Partnership and includes many possible actions that lead to increasing pollinator survival and/or awareness. This year, Pollinator Week will be happening June 20-26. One can participate in activities already organized by others, or one can propose and host an activity! If you would like to get together with your community and organize an event, do it, and then submit it to the Pollinator Week event list! That way, others will know about it and will participate as well! To submit (or participate in) an event, go to the bottom of the Pollinator Partnership page.

Here are some activities happening in Maryland: bee hotel building workshop in College Park, MD, webinar in Greenbelt, MD, pollinator catch-and-release in Saint Leonard, MD, and several activities in Howard Co., MD.

Pollinator Week, June 20-26, 2022 logo

3. Ask your city to host a No-Mow Month in early-spring

Early-spring pollinators emerge usually when very few plants are flowering, meaning that the early spring is a critical time for these pollinators. In human-occupied landscapes like cities or suburban areas, a lot of the landscape is occupied by lawns, which can provide some flowers early in the spring. No-Mow Month (usually April or May, depending on the city’s conditions) is an action that seeks to allow the availability of the early flowers in lawns so that local pollinators can survive during the early spring. Once other plants in the landscape start flowering (usually at the end of April in most of Maryland), the lawn can be mowed with this not negatively affecting pollinators.

It is important to note that this action is based on voluntary participation, meaning that participants opt-in (instead of being mandated to do it). This action has been shown to be effective in increasing pollinator diversity and abundance in regions where it is implemented, and is not associated with excessive lawn growth because it occurs so early in the season. Further, it can be strengthened with native plantings, which can boost its effects and also support local landscapers during the reduced-mow month. Localities where the action has been implemented tend to have high adoption rates, increased nature awareness, and willingness to further support biodiversity around homesteads, with no- to very-reduced vermin occurrence.

This action usually requires some temporal amendments to City Code (e.g., to ensure that participants will not be penalized if their lawns surpass the maximum allowed height during the no-mow month) so it needs approval by City Councils. Although this may sound really complicated, it is not, and several Cities in Maryland have implemented this program very successfully during the month of April (see here for College Park, MD, and here for Greenbelt, MD), following Appleton, WI’s trailblazing action. If you think this is something you would like to implement in your community, get in touch with these cities’ Bee City USA committees so they can share their expertise, and then contact your representatives to ask them to adopt this action where you live!

No Mow April Collage Park sign

4. Ask your community to establish pollinator-friendly plants and nesting resources

Communities can also support pollinators through the way they decide to landscape their land. Requesting your community leadership to implement pollinator-friendly gardens and offer nesting resources for pollinators (e.g., bee hotels, create small wild spaces) is a really good way to help pollinators at a larger scale. To do this, you can get in touch with you City/Town Horticulturist and/or Public Works people, and request this. If you would like to implement this in your neighborhood and on private land, you can coordinate with your neighbors and create plots of native plants or small nesting areas in everybody’s green spaces. A very effective way to do this in Maryland is by establishing a neighborhood Green Team. If you would like to know about how to do this, take a look at this page of recommended native plants and this list of native plants that do well in our area.

Chart listing easy-to-grow native plants that support pollinators

5. Ask you city/town/neighborhood to adopt an IPM plan

Although we tend to think about helping pollinators only by planting flowers and maybe creating nesting spaces, pollinators also can be helped by the way we manage our landscapes. For example, herbicides and pesticides can be sometimes very harmful to pollinators, or cutting plants at certain times of the year can really negatively affect them. Reducing the use of pesticides and herbicides, or changing the way we manage our own private land is one possibility. However, cities, towns, neighborhoods, schools, and campuses also manage their public lands! For that reason, they can also implement actions to manage spaces in ways that support pollinators.

chart explaining Integrated Pest Management in 5 steps

A very good way to institutionalize this is by requesting these institution to implement Integrated Pest Management (IPM) plans. IPM is a way of controlling pests and increasing “beneficial” organisms in a given space by means that reduce the use of pesticides and herbicides. These plans establish a framework that allows institutions to still control pests and diseases, while reducing the negative impacts on biodiversity that some conventional practices have. These plans can be very general or very specific, and if your institution does not have one, it may be time to ask them to implement one! To do this, get in touch with your institutional horticulturist or your government representative. Here are some examples: city, campus and school district plans.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish-speaking friends and colleagues in Maryland. ¡Bienvenidos a Extensión en Español!

Q&A: Some insects have a lot of gall

Maple Eyespot Gall, caused by a native midge (tiny fly) that occurs throughout the state. Photo: M. Talabac

Q: What on Earth is going on with this maple leaf? I saw it on a wild tree while taking a walk down a neighborhood path, but wonder if it’s something that can spread to nearby gardens.

A:  This is a great example of a gall, which is a tissue deformity on a plant caused by either insects, mites, fungi, bacteria, or nematodes. Usually galls cause swelling or weird projections on leaves or plant stems, but sometimes the more obvious feature is a color change like this.

The activities of the organism responsible creates chemical changes in the leaf tissue, redirecting tissue formation to suit its needs. For instance, insect-made galls give the larvae their own little house to feed in while being protected from most predators or harsh weather. (Impressively, tiny parasitoid wasps, little bigger than a dash on this page, still find their prey inside these structures and interrupt their life cycle. Isn’t that amazing?)

Despite how drastic galls may look to us, they don’t cause much harm to their host plants, which can be trees, shrubs, or perennials. Oak trees are renowned for harboring many kinds of eye-catching galls, some of which become most noticeable when they fall out of the canopy onto our lawns or gardens. See if you can find anything living inside those swollen red or brown lumps or balloon-like pockets on leaves. A wise bird or other insect may have beaten you to it, though, or the culprit is long gone and already flew away as an adult before the plant jettisoned the injured leaf.

If an eyesore, you can clip off heaviest infestations of leaf galls on witchhazel (caused by insects), azaleas (fungus), oak saplings (usually insects), and any other easy-to-reach plant. Keep in mind that the unaffected portions of those leaves are still functioning to feed the plant, so don’t remove too much growth. Otherwise, I suggest you leave them alone and just marvel at the intricacies of the natural world. Gall-forming insects can feed songbirds and don’t risk the health of the plant. As with any organism, populations wax and wane over time and galls might be prevalent one year and nearly absent the next.

At the Home and Garden Information Center, we have several web pages with more information about galls, including Shade Tree Galls and Eyespot Galls on Trees.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun. Read more posts by Miri.

Have a plant or insect question? University of Maryland Extension has answers! Send your questions and photos to Ask Extension.

Bees to look out for: leaf-cutter bees!

Spring is well-established and many flowers have already started to bloom. In my garden, I have seen several sizes and shapes of insects visiting flowers, going from small flower flies to butterflies, to very tiny and shiny, fuzzy large, and very large bees. And with all these flying organisms starting to come around us, I thought today would be a really good time to introduce you to some really cool bees that are very common in our area: the leaf-cutter bees!

What are leaf-cutter bees?

As its name suggests, these are solitary bees known to cut leaves (now you may be thinking, “duh, I could have guessed that without a blog post”, but bear with me!). These bees belong to a very large family of bees called Megachilidae, which is present on all continents except Antarctica and well-represented in our region.

Like most solitary bees, the female of leaf-cutter bees builds nests with small brood cells, in each of which a food provision is left and one egg laid. And this is where the “leaf-cutter” name comes from. When building their nests, many of these females line their brood cells with specific materials, in particular plant tissues. In fact, many of the species are known to cut leaves and/or petals to line their nests, using them to stabilize the brood cells, and likely to provide protection to the larva and the food provisions. In a fascinating way, it is suspected that these bees are able to exploit the antimicrobial effects of certain compounds present in these flowers and leaves, indirectly using them to protect their offspring until they finish their development in the nests.

If you ever saw neat and relatively large holes that seem to suddenly pop up on certain plants in your green spaces, it is very likely that they were made by some of these bees that may be nesting close to you! If you keep an eye out on those plants, it is very likely that you will end up seeing these busy bees carefully cutting, then rolling, and finally flying away with the neat plant circles!

Female leaf-cutter bee cutting a leaf
Leafcutter bee nest and brood cells made with leaf pieces
Megachilids are known for cutting leaves that they use to line the brood cells of their nest. Note that here the nest is in a soil mound and each brood cell is completely covered with leaves but capped and separate from the neighboring cells. In this nest, each cell contains one egg. Photo: E. Soh.
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Houseplants – The Garden Thyme Podcast

two houseplants on a windowsill

Happy New Year! It is hard to believe that we are already in a new year. We are kicking off our third season by sitting down with Extension Educator Ginny Rosenkranz. Like many of you, during the pandemic our acquisition of houseplants increased exponentially. Ginny guides us on caring for all of our botanical beauties.

We also have our: 

  • Native Plant of the Month, Musclewood, Ironwood (Carpinus caroliniana) at ~24:55
  • Bug of the Month, Ice crawlers or ice bug family Grylloblattidea at ~29:05
  • Garden Tips of the Month at ~31:50

To listen to the podcast visit https://www.buzzsprout.com/687509.

podcast sound wave image

We hope you enjoy this month’s episode and tune in next month for more garden tips.

  1. If you have any garden related questions please email us at UMEGardenPodcast@gmail.com
    or look us up on Facebook at https://www.facebook.com/GardenThymePodcast.
  2. For more information about University of Maryland Extension and these topics, please check out the UME Home and Garden Information Center website at https://extension.umd.edu/hgic.

The Garden Thyme Podcast is a monthly podcast brought to you by the University of Maryland Extension. Hosts are Mikaela Boley- Senior Agent Associate (Talbot County) for Horticulture, Rachel Rhodes- Agent Associate for Horticulture (Queen Anne’s County), and Emily Zobel- Senior Agent Associate for Agriculture (Dorchester County). Theme Song:  By Jason Inc.

Planning your garden to support specialized pollinators

Looking out my window, as the ground is covered with snow and I am getting ready for another snowstorm coming tonight, it seems ironic that I have been spending many hours these days ordering seeds and planning my garden. While I am thankful that the winter brings some rest to the soil in my garden, planning this season brings me happy memories of the scents and buzzes in my yard during the growing days… which reminds me that I should also plan for my little buzzing pollinator friends when I plan what to grow this season. In today’s blog, I want to chat about how we can plan for many types of pollinators, with a special focus on planning for specialists and not just for generalist pollinators.

Specialist pollinators – never heard of them?

As we mentioned in a previous post, pollinators visit plants to feed on nectar and/or to collect pollen to feed themselves or their offspring. However, pollen is not just there for pollinators to feed on; pollen is central to plant reproduction, so plants tend to make it both attractive to pollinators but hard to digest. For this reason, and in order to be able to properly digest the pollen, pollinators are often specialized in their pollen choices. This is because being able to digest the compounds that plants add to their pollen to make them hard to eat requires some level of adaptation, which often involves a trade-off with the ability to eat anything. There are, of course, many levels of specialization, and, while many pollinators feed on many plant families, others are more specialized than that, and feed on only specific plant genera or even species! For us gardeners, this means that if we want to support many different pollinators, we need to make sure that we are also providing for those very specialized pollinators as well!

Luckily for us, the floral choices and pollen specialization is known to some extent for Maryland and Eastern USA bees (see this site to learn more). For this reason, we know that many specialized bees in our region are also rare or uncommon… another reason to try to provide resources for them!

Who are pollen specialists in our region?

Many known pollen specialist bees in our region belong to bee genera Andrena, Colletes, Osmia, and Melissodes, which have many species considered rare or uncommon in Maryland and Mid-Atlantic.

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How do pollinators find plants and flowers?

As we know, pollinators help plants spread their pollen among flowers, and many plants do indeed need them to be able to reproduce and set seeds. We also know that by planting flowers and providing nesting habitats, we can help pollinators’ populations and thus assist with plant pollination. However, how do pollinators find plants? In this post, we will talk about that topic, which can help us become even better at helping pollinators and the plants they pollinate.

The big picture – pollinators need to be in the area

In order for pollinators to find plants, pollinators need to be present in the general region. In fact, although the vast majority of pollinators can move and travel from place to place, all of them have limitations on the distance they are able to travel. For example, hummingbirds can travel for miles (in Maryland, they are migratory), while large bees are able to travel relatively large distances for an insect (~500m-1km), and smaller insects will not be able to travel that far. This means that if, say, we lived in the middle of a very developed area with very few pollinator-friendly resources (few flowers, lots of cement, no green areas, etc.), planting a pollinator garden will attract few pollinators at first. This is due to the fact that it is likely that few pollinators are present in that area, and thus it will take a while for certain groups to arrive and establish in our garden.

It is for this reason that many communities tend to try to establish joint pollinator-friendly actions, and encourage many people in the region to participate (e.g., becoming Bee City USA-certified, creating “pollinator highways or corridors”). By increasing the regional number of pollinator-friendly resources, the whole region becomes more pollinator-diverse, and any supplementary action is more likely to improve pollinator support. As we talked about in a previous post, if you are interested in promoting pollinator-friendly habitat on your property, it may be a great idea to talk to your neighbors or your City, and see if others may also want to participate. In terms of pollinator-friendly activities, the saying “the more, the merrier” is very much true!

pollinator habitat sign in a garden
Pollinator-friendly actions are very effective when they are coordinated across regions. Photo: A. Kokai.

The local picture – different pollinators prefer different plants

As we mentioned in other posts, not all pollinators are made equal, and this is also true in terms of what plants will be found by what pollinators. For example, hummingbirds tend to visit tubular and reddish flowers, while syrphids prefer open flowers, and bees tend to visit flowers that they can access with their mouth parts (see this post to learn more). 

These floral preferences are due to the different pollinators’ abilities to see different colors, the presence of specific attractive floral scents in different plant species, and the ability of different pollinators with different body and mouth part shapes to handle and feed on flowers, and the matching of pollinator presence and flowering time. The practical consequence of this is that if we want to help many different pollinators find their preferred plants, it is necessary to grow different types of plants in our green spaces. By doing this, we would always provide resources that will be preferred to at least one pollinator, and by providing different types of resources, we can make sure that many different types of pollinators are supported by our plants. In order to do this, there are different floral mixes that exist that allow us to plant diverse floral resources appropriate for our region, which lets us build a diverse and welcoming floral bed for many pollinators.

Planting diverse floral resources will attract many different types of pollinators. Photo: C. Celley/USFWS.

The super-local picture – pollinators need to see the plant to access it

This will sound silly, but pollinators need to be able to have access to the plant to find it. For example, if a plant is not clearly displayed or hidden by many other plants or structures, it will be hard for pollinators to find it… even if the pollinator is present in the area and the plant in question is a preferred plant. This means that for us to help pollinators, we need to make sure that our plants are findable by the pollinators. Picking appropriate parts of our green spaces to plant our pollinator-friendly plants is thus key! For example, plants that require full sun to grow should be planted in those conditions and not under the shade of other plants or behind structures.

To know what these specific conditions are, there exist several resources (for example, see this useful and simple resource (PDF) published by the City of College Park, MD). These resources allow us to pick the best growing spot for our plants, making them easily findable by their pollinator friends.

Finally, pollinators are more likely to find plants if there are several of them! This is particularly true for smaller herbs, which may not display many flowers. By increasing the number of plants planted in an area we are also making the plant species more easily findable to the pollinators.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí. Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish-speaking friends and colleagues in Maryland. ¡Bienvenidos a Extensión en Español!