Potato plants have brown dead leaves and stems are drying up - Ask Extension
This is my second year growing portaoes. My first year was a moderate success. I planted about 4 lb. of organic Norkota seed potatoes in early to mi...
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Potato plants have brown dead leaves and stems are drying up #356554
Asked August 25, 2016, 4:20 PM EDT
This is my second year growing portaoes. My first year was a moderate success. I planted about 4 lb. of organic Norkota seed potatoes in early to mid June 2015. In early October 2015 I dug up approx. 26 lbs. of potatoes. Most of them were huge...one weighted 1 lb. 9 oz. A lot of them had cracks in the center, but I didn't mind...I cut that part away. They were delicious compared to store bought potatoes.
This year I planted 5 lb. organic Norkota potatoes on May 13. The plants were huge and very healthy and beautiful. All plants were hoed up before blossoming. I hand-picked all potato beetles at least twice a day until they were totally gone.
For the last several weeks the leaves on all plants are turning brown and dry. The stems are yellowing and/or getting brown. I dug up two plants that had no leaves and dry stems and found seven 3" to 4" potatoes, several golf ball size and six or seven cherry-sized potatoes. The larger potatoes were still attached to the vine. I am pleased to see they are in perfect condition...i.e., not any signs of disease. I was sorry I dug them up because I thought maybe they would have developed more if left in the ground. But then I wondered...do they need a healthy stem to continue to mature?
At this point I want to know....should I just leave them in the ground until late September or should I dig them all up now?
I appreciate any advice you can give as to what you think happened to make the plants die out. Is this a normal process for the amount of time they have been in the ground? Or do they have some sort of blight and they just stopped growing: And now I should dig them all up or what?
Thanks in advance for your help,
Marjorie Geiger
South Canaan, PA
Wayne County Pennsylvania
Expert Response
Potatoes are susceptible to a bacterial wilt called verticillium wilt. Here is a link to a publication that explains the symptoms. I would also look for environmental causes. The heat spell we just had could be a cause. I lost some melon vines in exactly the same way. They withered and turned brown with the immature melons still attached. Potatoes are a cool weather crop, so it's possible that they couldn't handle the recent high temperatures. Here is a quote from a publication on potato temperature requirements
"Potatoes are cool season crops which grow best in cooler climates or as a winter crop in areas with warm summers. They are sensitive to heat but can tolerate a light frost. Potatoes require a deep, fertile, loose, well-draining soil with a pH between 5.8 and 6.5 and will grow optimally at daytime temperatures between 18 and 27°C (65–80°F) and night time temperatures between 12 and 18°C (55–65°F). "
It's also possible they didn't get enough water. Although we had plenty of thunderstorms, we didn't have many soaking rains. Here is a quote about moisture requirements.
"Potatoes are sensitive to soil moisture and grow best when soil moisture is consistent. The plants generally require about 1 inch of water a week from rainfall or irrigation. Water-saturated soil should be avoided as it can poorly formed tubers and rot. In addition, potatoes are heavy feeders and the addition of a balanced fertilizer every two weeks can help increase tuber yields."
Once the vines are dead, there is nothing left to feed the potatoes. I recommend you dig up any potatoes that are attached to dead vines. Perhaps some of the crop will be suitable as seed for the next growing season. Also, you can take a sample of the vine into your local Penn State Extension and have it analysed for possible disease. The plant clinic will send you a report and recommend any remedy they think is necessary.
With the tricky weather conditions we have had in the last couple of years, it is a good idea to invest in a rain gauge so you can monitor the amount of water your crop is getting. I also put in a low tunnel made of PVC flexible conduit and used clothespins to attach sheer curtains from the local box store. This gave my heat sensitive plants some shade during the hot spell. There are lots of directions on the internet for cheap ways to make a low tunnel.
"Potatoes are cool season crops which grow best in cooler climates or as a winter crop in areas with warm summers. They are sensitive to heat but can tolerate a light frost. Potatoes require a deep, fertile, loose, well-draining soil with a pH between 5.8 and 6.5 and will grow optimally at daytime temperatures between 18 and 27°C (65–80°F) and night time temperatures between 12 and 18°C (55–65°F). "
It's also possible they didn't get enough water. Although we had plenty of thunderstorms, we didn't have many soaking rains. Here is a quote about moisture requirements.
"Potatoes are sensitive to soil moisture and grow best when soil moisture is consistent. The plants generally require about 1 inch of water a week from rainfall or irrigation. Water-saturated soil should be avoided as it can poorly formed tubers and rot. In addition, potatoes are heavy feeders and the addition of a balanced fertilizer every two weeks can help increase tuber yields."
Once the vines are dead, there is nothing left to feed the potatoes. I recommend you dig up any potatoes that are attached to dead vines. Perhaps some of the crop will be suitable as seed for the next growing season. Also, you can take a sample of the vine into your local Penn State Extension and have it analysed for possible disease. The plant clinic will send you a report and recommend any remedy they think is necessary.
With the tricky weather conditions we have had in the last couple of years, it is a good idea to invest in a rain gauge so you can monitor the amount of water your crop is getting. I also put in a low tunnel made of PVC flexible conduit and used clothespins to attach sheer curtains from the local box store. This gave my heat sensitive plants some shade during the hot spell. There are lots of directions on the internet for cheap ways to make a low tunnel.
Thank you so much.
I will take a stem sample to my extension office in Honesdale. As the stems die, I will dig up the potatoes.
The information re potatoes are a cool weather crop is most helpful...love the curtain idea. Now that you mention the summer heat, I do believe that is what happened. The potatoes were fine till the first mini heat wave...then the problem began. Once we went into the really hot temps I had to water the plants. We did have quite a bit of rain in my area following and during the heat wave. My potatoes were planted deep though. I'm going to make adjustments in my potato bed location next year to provide a cooler spot, mid-afternoon shade and breezes.
I went on the link for wilt. My potatoes have no black spots or lines at all...thankfully. I will save the smaller potatoes for seed potatoes....great tip! Marjorie Geiger
I will take a stem sample to my extension office in Honesdale. As the stems die, I will dig up the potatoes.
The information re potatoes are a cool weather crop is most helpful...love the curtain idea. Now that you mention the summer heat, I do believe that is what happened. The potatoes were fine till the first mini heat wave...then the problem began. Once we went into the really hot temps I had to water the plants. We did have quite a bit of rain in my area following and during the heat wave. My potatoes were planted deep though. I'm going to make adjustments in my potato bed location next year to provide a cooler spot, mid-afternoon shade and breezes.
I went on the link for wilt. My potatoes have no black spots or lines at all...thankfully. I will save the smaller potatoes for seed potatoes....great tip! Marjorie Geiger
I think it was the heat because some people lost tomatoes, some lost melons. Even heat lovers like peppers looked a bit ragged. Also, you may want to check on varieties that are able to withstand problems. If you talk to the Master Gardeners when you go to the extension, see what varieties they are planting. That kind of advice helped me a lot.
