I live in Toronto and have a raised bed vergetable garden in the back yard. I added lots of manure in the early spring, then I sowed squash seeds in the early June; however, eventually they were infected by disease and I had to remove all from the garden. I am thinking of sowing vegetable seeds that can be harvested in a fall in the same place. My concern is that if the soil needs to be amended by adding some fertilizers to make the soil better condition. or can I sow vegetable seeds directory in the same garden even though previously planted vegetables were affected by a plant desease?
Having a vegetable garden is one of life’s great pleasures! And a raised bed offers many advantages for growing. It sounds like you are doing the right thing for the garden already by adding manure, which is organic matter that feeds the soil, and therefore the plants, and eliminates the need for chemical fertilizers. This is a practice that you should continue.
I am afraid that fertilizers will not treat the disease problems that afflicted your squash seeds. It may be an insect problem or a virus or wilt that afflicted the squash family, Cucurbitaceae. Start with good sanitation practices in your garden and remove all of the infected plant material and destroy it or place it in the trash. Do not compost infected material. Then ensure that you buy disease resistance strains of the various vegetables that you want to grow, whether they be seeds or plants. There are many available.
The next thing to consider is crop rotation. Many diseases are soil-borne and exist in the soil for several years. Vegetable crops in the same botanical family are often host to the same diseases or insects. By rotating the plants around your garden there is less chance of disease problems. While your garden may be small and this may seem difficult, even moving them a few feet away will help. Therefore it would be unwise to plant cucumber, pumpkins, gourds or muskmelon where your squash seeds had been, as they are all in the same family.
Here are some articles that will add additional information on all of these topics:
Managing Diseases in Home Vegetable Gardens
Crop Rotation in the Vegetable Garden
Organic Vegetable Gardening