the orchards specified in the agreement. To the extent growers under contract produce more walnuts than we anticipate, we would still be required to purchase the entire output, which could lead to an over supply situation in which we may be forced to carry more inventory than we can profitably sell. Similarly, if growers under contract produce fewer walnuts than we anticipate, or if a significant number of growers decide not to renew their contracts as they expire, our supply of walnuts would decline, which would constrain the amount of raw material we have to process and sell. Any significant over supply or shortage of walnuts could adversely impact our operating results.
We face intense competition from national and regional competitors and snack food industry competitors that could negatively affect our results of operations.
We operate in a highly competitive environment. In general, competition in our markets is based on product quality, price, brand recognition, and brand loyalty. Our products compete against food and snack products sold by many regional and national companies, some of which are substantially larger and have greater resources. We also compete for shelf space in retail grocery, convenience, drug, mass merchandiser, and club stores. As these retailers consolidate, the number of customers and potential customers declines and the purchasing power of the consolidated retailers increases. As a result, there is also greater pressure to manage distribution capabilities in ways that increase efficiency for these large retailers, especially on a national scale. Our competitors with greater resources may be in a better position to meet these requirements. If we cannot improve our national distribution capabilities, we might not be able to compete effectively and our sales may decline.
We compete in the highly competitive snack food industry with our Emerald brand snack product line. Some channels through which we sell our Emerald products, such as drug and convenience stores, are different than those that we typically use for culinary and in-shell products, and we have less experience in these channels than our competitors. Furthermore, to compete in other channels, such as club stores, the sales cycle can be extended one year or longer and may require displacing incumbent vendors who have longer relationships with the buyers. Our principal competitors in the snack industry have substantial financial, marketing and other resources. If our competitors lower their prices or increase their promotional spending, or we are unable to compete effectively, our growth opportunities, margins and profitability may decline.
Our snack business currently generates minimal gross margins. If we are not successful in increasing snack sales and lowering unit costs, we may not be able to increase our profitability.
Sales to our top customer represented approximately 19% of our net sales. The loss of any major customer could adversely impact our business.
We depend on a few significant customers for a large proportion of our net sales. This concentration has become more pronounced with the trend toward consolidation in the retail grocery store industry. Sales to Wal-Mart Stores, Inc. represented approximately 19% of total net sales for the year ended July 31, 2007. Sales to Costco Wholesale Corporation represented 10% of total net sales for the year ended July 31, 2007. The loss of a significant customer or a material decrease in purchases could result in decreased sales and adversely impact our net income.
Because we experience seasonal fluctuations in our sales, our quarterly results will fluctuate and our annual performance will depend largely on results from two quarters.
Our business is highly seasonal, reflecting the general pattern of peak consumer demand for nut products during the months of September, October, November, and December. Typically, a substantial portion of our revenues are earned during our first and second fiscal quarters. We generally experience lower revenues during our third and fourth fiscal quarters and in the future may incur losses in these quarters. Sales in the first and second fiscal quarters accounted for approximately 60% of our revenues for the year ended July 31, 2007. If sales in these quarters are lower than expected, our operating results would be adversely affected, and it would have a disproportionately large impact on our annual operating results.
Changes in the food industry, including changing dietary trends and consumer preferences, could reduce demand for our products.
Consumer tastes can change rapidly due to many factors, including shifting consumer preferences, dietary trends, and purchasing patterns. Our growth is largely dependent on the snack industry, where consumer preferences are