The joke in Maine is that when August comes around it’s best to lock your car doors, otherwise you’re likely to find a pile of zucchini on the back seat when you get back. With such a glut of zucchini, it’s hard to believe that these popular vegetables are subject to a whole host of destructive diseases.
Following are descriptions of some of the most common diseases of zucchini, with tips for controlling them and links for more information.
1. Phytophthora blight
Phytophthora blight is a serious fungal disease that affects members of the cucurbit, or squash, family, including zucchini. It causes damping off of seedlings, leaf spots, foliar blight, root rot, crown rot, fruit rot, and stem lesions.
Gardeners can manage phytophthora blight by planting zucchini in well-drained fields. To prevent the blight from spreading it’s important to separate zucchini from other susceptible crops such as eggplant, tomato, and other squashes. Gardeners should also (1) plant zucchini in hills or domes, rather than on flat ground; (2) use resistant varieties; and (3) clean tools and shoes to avoid spreading the disease.
For more information on phytophthora blight on cucurbits check out this university of Cornell extension article.
2. Plectosporium blight
Plectosporium blight is a fungal disease that can overwinter in the ground for a number of years. The spores are spread by the wind. Cool, rainy weather promotes the spread of this blight. Gardeners can recognize the disease by the white, diamond-shaped lesions on vines and round lesions on fruit and leaves.
In severe infestations the vines and leaf petioles turn white and the leaves die. Lesions allow rot pathogens to infect the fruit.
Home gardeners can manage the disease by using trickle irrigation instead of overhead watering, plowing under crop residue after harvesting, employing a three-year crop rotation, and ensuring good air circulation in the fields. With large crops gardeners may decide to use fungicides in addition to these management techniques in order to control the disease.
You can find more information on plectosporium blight, including photographs, at this UMass extension website.
3. Squash mosaic virus (SqMV)
Squash mosaic virus (SqMV) is a seed borne disease spread by the spotted and striped cucumber beetles. Infected mature leaves show blistering, hardening, and a green mosaic (mottling) pattern. Leaves of young seedlings appear distorted and pale in color. Planting disease-free seed and controlling the cucumber beetles can stop SqMV.
For more information on SqMV, you can read up courtesy of the Ohio State University Extension.
4. Zucchini yellow mosaic virus (ZYMV)
Zucchini yellow mosaic virus (ZYMV) is another one of a number of diseases that cause the leaf mottling known as mosaic. ZYMV is transmitted by aphids, which carry the disease on their probing mouthparts. Pokeweed and other weeds harbor viruses and serve as hosts for the insects that transmit viruses.
Controlling aphids as well as weeds around gardens can help manage the disease. The best control, however, is to plant mosaic-resistant varieties.
This will help you learn more about ZYMV and other mosaic viruses of cucurbits.
Cornell University’s Department of Plant Pathology also has an excellent fact sheet (with photographs) called Viral Diseases of Cucurbits.
Creative Commons Flickr photo courtesy of Jeremy Keith
there is a black film on the stem at the base of my zuchinni and on one of my top stems , what should i do?
thanks,
Ann Kenderson
Pgh, Pa
Our zucchini plants are really starting to produce. We are noticing a few differences than normal, soon after the fruit forms and starts to grow the skin turns dark green and is tough (just like when you leave the zucchini on the plant to long and you end up with a base ball bat) and end of the fruit is much smaller and eventually turns yellow and shrivals.
I have a white substance on the tops of my zucchini plants. Is this a disease? I cut back the leaves because they were so large I thought maybe they were crowding out the light from the bottom of the plant where the vegetable is. I still see them growing but one was rotten halfway down.
I use peroxid amd water to cure the mold . Two cuos to a gallon of water and spray the leaves and pour around the base . peroxid has 2 oxygens 1 hydrogen . very good for plant growth . dont make it too strong or may burn the leaves . just make it strong enough though . 4 tables spoons wont due per gallon .
zucchini in our area are producing one fruit and then dying whats going on? Not just in one area but in surrounding towns as well.
My zucchini fruit grow to about 3 inches long and then die off. Does anyone know what causes this?
With regards to the small fruit dying off, I learnt from this video (http://www.youtube.com/watch?v=3x1crwrsxj8) that my problem was lack of pollination. I hope this helps other people
I am not sure, but it may be pollination problem. May be increase the number of honey bees around your garden. I planted lots of PINK Oxalises for their beauty and was happily surprised as each plant (about 24″ in diameter in average) has 100s of tiny pink flowers and 5-10 bees on each plant
My courgettes are growing very nicely but when I harvest them they are rock hard. If I cut them open they look normal in the centre but a different colour toward the skin of the fruit. Is there something I am doing wrong?
Our plants are growing well- The fruit doesnt grow past 3 to 5 inches, turns yellow on the end and quits growing. Whats up
Like Sarah Kranning last August, my zucchini produced 2 or 3 fruits and died. Did any one find an answer for this problem?
Hello,
Two weeks ago I planted four zucchini in large tubs on my deck. I used Gardner’s Gold compost/potting mix. The plants are huge, and I’m seeing some small blossoms appear. Should I be worried about vine boring worms? I haven’t see any signs of them, and I had hoped that by planting in pots that I might alleviate the boring bug problem. Any comments/suggestions would be most welcome. Thank you.
I have a problem with my Zucchini plants. They are growing in raised beds, I put ground covering material over them from the day they were planted until they started to bloom. I also mulched with straw, but they still have some kind of a disease. I have spent many hours on the internet looking for a solution. Your website, and most others, list many problems and diseases but I’m not sure which disease I’m dealing with. Why don’t you show pictures of each type of disease. It would be so easy to match up a picture with my plants. My problem started with silver spots on the leaves. NOT powdery mildew. The spots have no texture and do not rub off. But now, almost overnight, the leaves are turning yellow and brown on the edges, are are curling up and dying quickly. We have had a lot of rain lately, but I’m not sure if that is the problem. I’m an organic gardener and do not spray chemicals. What is my problem and are there any organic solutions? Please help!
For Zucchini problems, I recommend doing these tips- https://www.gardenloka.com/zucchini-growing-problems/.. Works well with me..
My zucchini fruit has small white pimple bumps on them are they safe to eat
Have the same issue with small white pimples on squash. Any answers yet?
the zucchini fruits are having a small patch of rotten hole, when opened there is no worms, the leaf and root looks fine, but this one single rotten hole that goes few inches deeper and the inside area is darken(rotten) that goes few inches radially.