Common Plant Problems

What's Wrong With My...?


COMMON VEGETABLE PROBLEMS

By Jolene Wallace, Horticulture Specialist, CCE Clinton.


SQUASH

What’s wrong with my… squash?

As you probably know, squash is a cucurbit, as are cucumbers, melons, and pumpkins. They are members of the gourd family. But that’s not all they have in common.

I frequently hear from folks who want to know why their squash (cucumber, melon, pumpkin) plant has plenty of flowers but is not producing fruit. You may be surprised to find out why this happens. It’s a pollination issue.

Cucurbits are monoecious, meaning they have male and female flowers on the same plant. The male flowers typically appear first, except for zucchini and summer squash, when the female flowers may bloom first. Until the female flower is fertilized, there can be no fruit.

To make it more confusing, if it’s too hot, too wet, too whatever, and not enough something else, the female flower, or male flower, may never bloom. For sure you won’t get fruit then.

Let’s assume we have male and female flowers, eventually at the same time. This photo from the University of Maryland Extension shows how they differ. 

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If you also have bees, nature will take its course and you will eventually have cucurbits. If you don’t, hand pollinating is an easy option, but can be back-breaking work.

CUCUMBERS

If your cucumber plants look like this,

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and your cucumbers like this,

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you have cucumber beetles. There are spotted cucumber beetles and striped cucumber beetles. The striped are more common in our area. 

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                                   Striped Cucumber Beetle

They not only chomp on the leaves and flowers of your cucumber plant, they are capable of transmitting bacterial wilt. The beetles acquire the bacteria by consuming plants already infected with it. Not all beetles carry the bacteria, but if they are contaminated they transmit the bacteria by their mouthparts or feces. Once the bacteria are transmitted to the plant they begin to reproduce. The plants will eventually die.

To determine if a plant is infected with bacterial wilt, press together two freshly cut sections of a stem and slowly pull them apart. If a "stringy" sap (bacterial growth and associated resins) extends between the cut ends, the plant has bacterial wilt.

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Photo courtesy of M.P. Hoffmann, Cornell University       

TOMATOES 

Septoria Leaf Spot/Early Blight


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                                              Septoria Leaf Spot

Septoria Leaf Spot is a very common fungal disease of tomatoes potatoes, and eggplant. This disease manifests on the bottom leaves of the plant and work their way up. Remove the affected leaves as they occur. Water at the root level to avoid splashing spores on the leaves. A fungicide specifically made for use on tomatoes will slow the disease.   

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                                        Early blight on tomato leaf 

We frequently lump septoria and early blight together as they both manifest from the bottom leaves up, are both fungal diseases, and the treatment is pretty much the same. Below are signs and symptoms of early blight.

Signs and symptoms of early blight

  • Initially, small dark spots form on older foliage near the ground.
  • Leaf spots are round, brown and can grow up to half inch in diameter.
  • Larger spots have target-like concentric rings. The tissue around spots often turns yellow.
  • Severely infected leaves turn brown and fall off, or dead, dried leaves may cling to the stem.

  • NOTE: EARLY BLIGHT DOES NOT REQUIRE REMOVAL OF THE ENTIRE PLANT. THAT’S LATE BLIGHT, A VERY DIFFERENT SET OF SYMPTOMS. IF YOU SUSPECT LATE BLIGHT, TAKE A SAMPLE TO THE EXTENSION OFFICE FOR VERIFICATION BEFORE REMOVING PLANTS.

    Blossom End Rot

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    Figure 2: Varying degrees of damage seen on tomato fruits, (provided by the Plant Disease Diagnostic Clinic, Cornell University).

    Blossom end rot manifests as its name suggests. The part of the tomato, (pepper, zucchini, eggplant) at the farthest point from the stem is the blossom end.

    You will find some sites, or gardening articles, that tell you blossom end rot is caused by a lack of calcium in the growing tomato. However, it’s unlikely here in the North Country, that our soils lack adequate calcium. The problem is getting the calcium from the roots into all parts of the plant. That takes consistent watering.

    Factors that influence the uptake of water and calcium by the plant have an effect on the incidence and severity of blossom end rot. The disease is especially prevalent when rapidly growing, succulent plants are exposed suddenly to a period of drought. When the roots fail to obtain sufficient water and calcium to be transported up to the rapidly developing fruits, the latter become rotted on their basal ends. Another common predisposing factor is cultivation too close to the plant; this practice destroys valuable roots, which take up water and minerals. -- Cornell

    Control of blossom end rot is dependent upon maintaining adequate supplies of moisture and calcium to the developing fruit .If the weather forecast is for rain tomorrow but your plants need water today—water them!

    Last updated July 17, 2020