The Partenon Zucchini is putting out a lot of fruit, but I am encountering problems with fruit rot. The blossom end turns yellow and then rots back. Sometimes it starts even when the fruit is very small. So I am losing about 50%. I am harvesting the fruit smaller to try to get the fruit before the rot sets in.
I am not sure what is causing this. When I looked it up it suggesting
1. Poor Pollination. I am growing Partenon which does not require pollination.
2. Uneven watering causing blossom end rot. I have not been watering the zuchhini as much because of the rain. I do have plastic mulch so the fruit does not touch the soil, but the plastic could be holding puddles of water from the rain.
The pot stays wet from the rain, it is a plastic pot so it does not breathe ( I put extra holes in it). and the plastic mulch slows evaporation. I have not watered because the soil is wet. When the fruit rots it does not have the typical black rot at the blossom end of the fruit, so I don't think it is blossom end rot.
3. Fruit flies? It could be fruit flies but the fruit rots so badly that it is mush so I can't tell if maggots were in it. It is hard to tell if the fruits were stung. Most don't show signs of stinging.
What else could this be? I has been raining pretty much every day. There is also some powdery mildew on the older leaves, but this is a resistant variety so I can control that by removing the leaves.
I can't do anything about the rain. Temperatures are fine 64-78 degrees. I chose Partenon because it will set fruit up to 85 degrees.
I just started covering the fruit with net bags just in case they are being stung. Of course it only works if the bags go on before they are stung.
The leaves are small for zucchini and this is reused soil. So, I did add more lime, potassium, and nitrogen and I just did miracle grow yesterday for all the potted plants and the front yard. The vegetable garden does not need it.
The cucumbers in the reused soil are also showing nutrient deficiencies. The plants are small, but the cold and overcast weather may be contributing to that. I do see marginal yellowing, but no necrosis and some fungal disease on the older plants from the rain. The varieties I am growing for cucumber are Telegraph, Suyo, and Soarer. Telegraph is a new one. It is surprisingly resilient even with all the rain it has good mildew tolerance. I don't usually have to fungicide the resistant cucumbers. The others are the usual ones that I grow. Suyo has better heat tolerance but good downy mildew resistance and intermediate resistance to powdery mildew.
I just sent off soil samples yesterday from the reused soil. It is hard to guess what fertilizer I need. I did change the starter fertilizer to 1/2 cup 10-20-20 and 1 cup 6-4-6. Both have micros and 6-4-6 has slow N. It should be more phosphorus and potassium than 2 cups of 6-4-6 with micros, which is what I use for new soil.
I may have increased the pH a bit on some pots because I also added lime to boost the calcium ( about 1-2 tablespoons for an 18 gallon container). That could be suppressing the nitrogen and the micros. Hence I need to either do more frequent nitrogen applications or more water soluble fertilizer. I don't like to do that much work. I would rather figure out the best combination for the starter fertilizer to minimize the weekly supplements.
I also started adding crushed cinder to a couple of containers to boost the mineral content. It is neutral to alkaline but it does provide minerals. The amount is also small. about 1/4 cup per 18 gallon container.
My new potting mix that I make for general use and not for large containers has added osmocote. When I use reused soil, I don't add osmocote, so maybe I should. It would provide the slow nitrogen.
Then again, maybe I should hold off on this frustrating fertilizer guessing game and wait for the soil test results.
https://www.ctahr.hawaii.edu/tpss/diges ... 109_4.html
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