Nightshade Disease Reduction Strategies in your Hoophouse

by: Sara on 04/13/2019

In The Year-round Hoophouse: Polytunnels for All Seasons and All Climates, author Pam Dawling shares not only how to design, build and grow in your hoophouse, but the benefits of doing so. Pam's comprehensive guide explains how growing in hoophouses reduces the impact of an increasingly unpredictable climate on crops, mitigates soil erosion, extends the growing season and keeps leafy greens growing through winter. Today we share an excerpt about disease reduction strategies. Receive a 40% discount on this or any other New Society title when you order online at and use coupon code spring19 at checkout until April 15th.

Disease Reduction Strategies

Because nightshades have a lot of fungal, bacterial and viral diseases, it pays to take action to minimize the chance of diseases attacking your plants.

Here’s a checklist:

1. Choose disease resistant varieties  

2. Disinfect seeds with hot water against diseases that are seed-borne  

3. Consider grafting disease-prone tomatoes onto disease-resistant rootstock  

4. Practice good crop rotation  

5. Improve soil tilth, drainage and aeration  

6. Add compost and cover crops to help increase the diversity of soil micro-organisms and build naturally disease-suppressing soil

7. Practice good sanitation  

8. Remove nightshade weeds  

9. Use foliar sprays of seaweed extract, compost tea or other microbial inoculants to boost general disease resistance

10. Maximize air circulation around plants  

11. Provide good support  

12. Prevent soil splash-back

13. Plant a succession  

14. Use weather monitoring to minimize sprayings of copper compounds  

15. Try biofungicides for use against some tomato diseases

 16. Use bio-rational controls if needed, including AQ10, baking soda or milk against powdery mildew.

Physiological Disorders

These are caused by stress, not by pathogens, and can make tomato fruit unmarketable. See Chapter 27, Pests and Diseases, for more information.

The basics are:

• Blossom end rot (flat, dry black spot at blossom end): caused by a calcium deficiency in the fruit

• Cat-facing (pinched-in scars at the blossom end): aggravated by low or very high temperatures • Cracking: increased by erratic irrigation

• Green shoulders, gray wall, blotchy ripening, internal whitening are a related group of disorders caused by a shortage of potassium reaching the fruit —  consider side-dressing. Green shoulders are more common in some heirloom varieties than in hybrids, worse in hot weather

• Nutrient deficiency symptoms can sometimes look like a microbial disease. In conditions of fast growth and high yields under high diffusion plastics, plants can run out of potassium —  the lower leaves get much more light and plants grow taller, requiring more nutrients

• Puffiness and zippering (contracted linear scars): incomplete pollination at extreme temperatures

• Sunscald (bleaching and decay of fruit): usually caused by excessive defoliation.


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