Thursday, February 19, 2009

Zucchini revisited

A few weeks back I asked if any body had experienced Zucchini Black Jack growing rather attractive, but completely wrong, round fruit.

I had a number of responses to this question, fortunately no gardeners have had the same experience. I wonder now if our staff who took the plants home and reported the problem did not take plants that we had trial grown. We tested this seed first because it was old, my friend James had given me a stack of seed he no longer needed. Unfortunately the Zucchini did not germinate properly so we chose not to use it. Perhaps some members of our team, always on the lookout for a bargain snaffled the few plants that did grow.

Anyway, a number of correspondents did report Zucchini problems this season. In particular: “Why do some of them rot from the flower up? A customer swears that it's not a water problem and I must admit that a few of my own have done this but not all of them by any means.” I think, and a little research agrees that the symptom is very similar to Blossom End Rot in Tomatoes. Blossom End Rot is a response to irregular soil moisture, especially when transpiration rates are high (hot dry conditions). This problem is accentuated if the dry conditions are preceded by a period of high moisture (Think December in Melbourne). The fruit grows so quickly that the water requirement of the plant cells cannot be met, so the cells collapse. They may or may not then pick up a secondary infection.

Tricky problem to solve in the current climate, our rain water tank is now dry. The only real solution that I have is get right on top of your water management. Mulch! And don’t forget that drip irrigation systems are both highly effective and usable under the current water restrictions.


  1. Hello, Peter, our cucumbers are flowering and sometimes fruiting but fruits yellow at flower end and die I have tried hand pollinating them as they didn,t do anything for quite awhile but no joy any suggestiuns will be followed up faithfully thankyou Elsie

  2. Thanks Elsie,
    Your symptom sounds exactly like I'm describing in the blog post: a calcium imbalance possibly/probably caused by irregular soil moisture or as I have discovered from a South Australian this week salty water. Please note I'm saying irregular soil moisture, not lack of water. A lack of water will just produce nasty, shrivelled little fruit. Unfortunately improving pollination will not help fruit develop once it has been set.


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