Cooperative Extension Service McCracken County 2025 New Holt Road Paducah, KY 42001 (270) 554-9520 Fax: (270) 554-8283 extension.ca.uky.edu

Horticulture News in McCracken County

JULY 2020

Toolbox Garden Series:

A free class on the first Tuesday of each month at 5:00 p. m.

Protecting Your Cucurbits

Ric Bessin, extension professor, UK Department of Entomology

They may not bear a family resemblance, but cucumbers and pumpkins are closely related. They are cucurbits, a family that includes other popular garden plants such as zucchini, summer squash, winter squash, cantaloupe and watermelons. They all tend to take up a lot of room in the garden, so if you’re going to dedicate that much space you’ll want to reap as much fruit as you can. Yes, botanically, these are fruits, though we include many of them in our meals as vegetables.

The problem with cucurbits is that we’re not the only ones who enjoy them. Between insect pests and bacteria, plants in this family attract a lot of troublemakers. Striped and spotted cucumber beetles are the most common insect pests on all the cucurbits and will cause significant damage to seedlings and ripening fruit. They also transmit the bacterium that causes bacterial wilt, which hits cucumbers and melons particularly hard. Gardeners can be taken by surprise when wilt attacks; in the morning the plant can look healthy, but by evening a runner and its leaves have wilted irretrievably.

The best time to manage this problem is immediately after planting by applying a one-time soil drench of a systemic insecticide, which should provide three to five weeks of control. But if you didn’t apply the insecticide at planting, it’s still worth your time to scout for beetles and apply foliar insecticides as necessary to protect susceptible plants, particularly close to harvest. If you only have a few plants in your garden, picking off beetles by hand is another option, though you may have to do it daily, and it’s not a guarantee against wilt.

Squash beetle is a large lady beetle with 12 black spots on its back and an orange thorax. Whereas some lady beetles are beneficial and feed on pests like aphids, the squash beetle feeds on the underside of leaves, skeletonizing them, and can be a serious pest of squash and pumpkin. Apply foliar insecticides as necessary during the mid- and late season.

Then there’s the squash bug, which is brown and about 1-inch in length. They appear starting in June. They damage plants by dining on the sap, as well as causing leaves to wilt and collapse. Most detrimental, though, is that they carry the bacterium for yellow vine decline, which affects melons, watermelon and pumpkins. Foliar sprays targeting newly hatched nymphs are more effective than sprays used against the later stages of the insect. You may need to spray multiple times throughout the course of the growing season.

Keeping your cucumbers from having direct contact with the soil can prevent belly rot. When a cucumber lies directly on the soil, it can develop tan or brown lesions that resemble a dry rot. Using mulch as a barrier between fruit and soil helps. Also be careful not to overwater; overly wet soils can add to the problem.

With a little care, your homegrown cucumbers, squash and melons will thrive and give you a bountiful harvest and enrich your table.

For more information about cucurbit diseases and pests, check out the University of Kentucky Cooperative Extension publication, ID-128, Home Vegetable Gardening, http://www2.ca.uky.edu/agcomm/pubs/id/id128/id128.pdf, or contact the McCracken County office of the University of Kentucky Cooperative Extension Service.

30 June 2020 From: Bill Fountain, Extension Professor of Arboriculture and Landscape Management

Pluvial, the New Normal for Landscapes

One of the side effects I have noticed from our Covid-19 sheltering “new normal” is that people are spending a lot more time in their landscapes. With this has come a significant increase in questions to county agents and directly to me. People who garden often tend to be more observant of their plants than other members of society. People want to know names and if the plant is normal, safe, or has other problems. These newly awakened observation do not always transfer to recognition of long-term environmental conditions.

Today is June 30th the last day of the first half of the calendar year. It is a good time to look back to analyze what our

landscapes and gardens have been experiencing this spring and opine on what we might see later in the year. Rainfall on any given day will vary considerably across a large area like Kentucky. However, general trends are more consistent. This is why we look at averages. Rainfall at our house for June was 9.77 inches. Coupled with May this increases to a little over 18 inches; half of what the average annual rainfall would be for an entire year. When the rainfall from January first onward is added into May and June it comes to 48 inches; more than the average rainfall for an entire year. This trend, referred to as a pluvial period (long-term, wetter than historic averages) has been consistent for the past two years. What does this mean for plants?

Trees and shrubs form their fine roots, roots responsible for absorbing water and mineral elements where oxygen is present in the soil. When rainfall keeps the soil consistently wet, formation of these fine roots is going to be closer to the surface than in dryer soils. Late last summer we experienced a soil-cracking, record-setting drought. Many plants growing on wet sites had most if not all of their absorbing roots near the surface. Those plants that did not receive supplemental irrigation during the drought often suffered the detrimental effects of drought. The lessons for novice and experienced gardeners are:

● Monitor the daily rainfall. Write it down and it will help you see long-term trends.

● Check the soil moisture on a regular basis. This is especially important for newly installed trees and shrubs.

● When you notice that the soil is getting dry, don’t count on that rainstorm promised by the weather service two or three days from now. If the plants are dry now, put the sprinkler out - NOW.

● Match the cultural requirements of the plant to the conditions present on the site.

We gardeners always try to expand the palette of plants in our landscapes. If a plant is not suited to a site and we are not able to alter these cultural conditions then the plant is going to be more susceptible to disease and insect problems. It is estimated that approximately 80-90% of plant samples submitted to the Plant Disease and Diagnostic Lab have problems that can be traced back to cultural and soil problems. Key among these are water issues; amount, drainage, and ability of the plant to absorb water.

The new normal for Covid-19 sheltering in place has brought changes to all of our lives. One of these positive changes is likely to be a long term increase in interest in home landscapes and gardens and the health and social benefits of plants. We saw this after the Arab Oil Embargo of 1973-74 and before that with the World War II Victory Gardens. Timely, accurate information benefits all of us.

Bill Fountain

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William (Bill) M. Fountain

Professor of Arboriculture and Landscape Management

ISA Board Certified Master Arborist (KY-399B)

ASCA Registered Consulting Arborist (RCA #594)

ISA Tree Risk Assessment Qualified (TRAQ) & Instructor

CTLA Tree & Plant Appraisal Qualified (TPAQ) & Instructor

Department of Horticulture

Four shrubs with one in decline

Floral Design at the Biltmore,

March 2019