What's happening in the fall greenhouse?
In spite of the normal problems, the fall greenhouse tomatoes are coming along well. We expect harvest to begin around November 1st.
So what normal problems are we dealing with?
1- Whiteflies: After spotting these tiny white insects on the plants I contacted my supplier and ordered Encarsia Formosa, a parasitic wasp that parasitizes the white fly pupae. Two releases are necessary for good control with a two week interval between releases.
2- Excessive Heat: Temperatures in the 90's are not favorable to tomato pollination. As everyone in central NC knows we have endured many days in August and September above 90 degrees F. As a result fruit-set was slow initially.
3- Humidity and Disease: Any experienced NC greenhouse grower knows our late summer hot, humid days create plenty of night-time moisture in the greenhouse. Our most troublesome tomato disease, powdery mildew, thrives in these moist conditions. Even though we have been unable to conquer the powdery mildew we have always been able to produce a good crop in spite of it.
4- Cloudy Days: The arrival of much needed rain brought with it several cloudy days. In addition to aiding disease growth, cloud cover is also not favorable to tomato pollination. Again fruit-set has been temporarily hindered.
5- Cool Nights: Tomatoes need night-time temperatures above 55 degrees F for proper pollination. With night temperatures expected to dip into the 40's in a few days it is time to fire up the wood heater. Exercise, and plenty of it, will be a side benefit of hauling wood and maintaining a fire that will keep our tomatoes cozy.